Pattern forming apparatus and pattern forming method, movable body drive system and movable body drive method, exposure apparatus and exposure method, and device manufacturing method

ABSTRACT

A partial section of an aerial image measuring unit is arranged at a wafer stage and part of the remaining section is arranged at a measurement stage, and the aerial image measuring unit measures an aerial image of a mark formed by a projection optical system. Therefore, for example, when the aerial image measuring unit measures a best focus position of the projection optical system, the measurement can be performed using the position of the wafer stage, at which a partial section of the aerial image measuring unit is arranged, in a direction parallel to an optical axis of the projection optical system as a datum for the best focus position. Accordingly, when exposing an object with illumination light, the position of the wafer stage in the direction parallel to the optical axis is adjusted with high accuracy based on the measurement result of the best focus position.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a divisional application of Non-Provisional application Ser. No.11/708,611 filed Feb. 21, 2007, which claims the benefit of ProvisionalApplication No. 60/780,046 filed Mar. 8, 2006, the disclosure of whichis hereby incorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to pattern forming apparatuses and patternforming methods, movable body drive systems and movable body drivemethods, exposure apparatuses and exposure methods, and devicemanufacturing methods, and more particularly to a pattern formingapparatus and a pattern forming method that are suitable for being usedin a lithography process when manufacturing electron devices such assemiconductor devices and liquid crystal display devices, a movable bodydrive system, a movable body drive method, an exposure apparatus and anexposure method that can suitably be used when manufacturing theelectron devices, and a device manufacturing method in which theexposure apparatus, the exposure method or the pattern forming method isused.

Description of the Background Art

Conventionally, in a lithography process for manufacturing electrondevices (microdevices) such as semiconductor devices (integratedcircuits or the like) or liquid crystal display devices, exposureapparatuses such as a reduction projection exposure apparatus by astep-and-repeat method (a so-called stepper) and a projection exposureapparatus by a step-and-scan method (a so-called scanning stepper (whichis also called a scanner)) are mainly used.

In these types of exposure apparatuses, the wavelength of used exposurelight is getting shorter year by year due to finer integration circuit,and also the numerical aperture of a projection optical system isgradually getting larger (larger NA), to improve the resolution.However, there has been a possibility that the focus margin at the timeof exposure operation becomes insufficient because a depth of focusbecomes too narrow due to the shorter wavelength of exposure light andthe larger NA of the projection optical system. Therefore, as a methodof substantially shortening an exposure light wavelength and alsoincreasing (widening) a depth of focus compared in the air, an exposureapparatus making use of a liquid immersion method has been gatheringattention recently (e.g. refer to the pamphlet of InternationalPublication No. 2004/053955).

Further, as the requirement for overlay accuracy becomes stricter tocope with finer integrated circuits, improvement in positioncontrollability (including position setting performance) of a stage(wafer stage) on which an object to be exposed, for example, a wafer ora glass plate (hereinafter, generally referred to as a ‘wafer’) ismounted has been also required. Therefore, in the recent exposureapparatuses, the wafer stage has been downsized so as to be a slightlylager than the wafer, and another stage (which is also called ameasurement stage), which mounts various types of measuring instrumentsthat were mounted on the wafer stage before, such as a sensor thatreceives illumination light via the projection optical system (such asan illuminance monitor or an irregular illuminance sensor that receivesillumination light on an image plane of the projection optical system,and an aerial image measuring instrument that measures light intensityof an aerial image (projected image) of a pattern that is projected bythe projection optical system, which is disclosed in, for example, Kokai(Japanese Unexamined Patent Application Publication) No. 2002-014005)and the like), has been arranged separately from the wafer stage (e.g.refer to the pamphlet of International Publication No. 2005/074014). Inan exposure apparatus that is equipped with the measurement stage,various types of measurement can be performed using the measurementstage, for example, in parallel with wafer replacement on the waferstage, and as a consequence, the throughput can also be improved.Further, in this exposure apparatus, for example, a best focus positionof the projection optical system is measured using the aerial imagemeasuring instrument, and based on the measurement result, focusleveling control of the wafer stage (wafer) on exposure is performed.

In this case, however, a stage used for measuring the best focusposition and a stage used for the focus leveling control of the wafer onexposure are different, and therefore focus leveling control error couldoccur on exposure, and thus, exposure defect could occur due to defocus.

Further, position measurement of the wafer stage is generally performedusing a laser interferometer with a high resolution. However, positioncontrol of the stage with higher precision has been required due tofiner patterns to cope with semiconductor devices with higherintegration, and therefore, short-term fluctuation of measurement valuesof the laser interferometer which is caused by temperature fluctuationsof the atmosphere on the beam path is becoming unignorable now.

SUMMARY OF THE INVENTION

The present invention has been made in consideration of the situationdescribed above, and according to a first aspect of the presentinvention, there is provided a first pattern forming apparatus thatforms a pattern on an object with an energy beam via an optical system,the apparatus comprising: a first movable body that moves within apredetermined plane that includes a first axis and a second axisintersecting the first axis, holding the object; a second movable bodythat moves independently from the first movable body within the plane;and an aerial image measuring unit a partial section of which isarranged at the first movable body and part of the remaining section ofwhich is arranged at the second movable body, and which measures anaerial image of a mark formed via the optical system.

With this apparatus, since a partial section of the aerial imagemeasuring unit is arranged at the first movable body that holds theobject on which a pattern is formed, measurement of an aerial image bythe aerial image measuring unit while moving the movable body, andtherefore, measurement of optical properties of the optical system (suchas the best focus position) based on the measurement result of theaerial image can be performed. Accordingly, when forming a pattern onthe object with an energy beam via the optical system, the position ofthe first movable body in the optical axis direction of the opticalsystem is adjusted with high accuracy based on the measurement result ofthe optical properties. Further, since only a partial section of theaerial image measuring unit is arranged at the first movable body, thesize of the first movable body is not increased, which makes it possibleto favorably secure the position controllability.

According to a second aspect of the present invention, there is provideda second pattern forming apparatus that forms a pattern on an object,the apparatus comprising: a first movable body that moves within apredetermined plane that includes a first axis and a second axisintersecting the first axis, holding the object; a second movable bodythat moves independently from the first movable body within the plane; afirst measuring system that measures position information of the secondmovable body; and a second measuring system that measures positioninformation of the first movable body and whose measurement value hasshort-term stability superior to that of the first measuring system.

With this apparatus, position information of the second movable body ismeasured by the first measuring system, and position information of thefirst movable body that moves within a predetermined plane holding anobject is measured by the second measuring system whose measurementvalue has short-term stability superior to the first measuring system.Accordingly, position control of the first movable body that holds theobject on which a pattern is formed can stably be performed.

According to a third aspect of the present invention, there is provideda third pattern forming apparatus that forms a pattern on an object byirradiating an energy beam, the apparatus comprising: a first movablebody which moves within a predetermined plane that includes a first axisand a second axis intersecting the first axis, holding the object, andon which a first grating that has a grating whose periodic direction isa direction parallel to the first axis and a second grating that has agrating whose periodic direction is a direction parallel to the secondaxis are arranged; a second movable body that moves independently fromthe first movable body within the plane; a first measuring system thatincludes an interferometer that measures position information of thesecond movable body within the plane; and a second measuring system thatincludes an encoder system that has a plurality of heads to which thefirst and second gratings are severally placed facing, and measuresposition information of the first movable body within the plane.

With this apparatus, position information of the second movable bodywithin a predetermined plane is measured by the first measuring systemthat includes the interferometer, and position information of the firstmovable body within the predetermined plane is measured by the secondmeasuring system that includes the encoder system that has a pluralityof heads, to which the first and second gratings that are arranged onthe first movable body and each have a grating whose periodic directionis a direction parallel to the first axis or second axis respectivelyare severally placed facing. Accordingly, position control of the firstmovable body that holds the object on which a pattern is formed byirradiating an energy beam can stably be performed.

According to a fourth aspect of the present invention, there is provideda fourth pattern forming apparatus that forms a pattern on an object,the apparatus comprising: a movable body on which the object is mounted,and which moves within a predetermined plane that includes a first axisand a second axis intersecting the first axis, holding the object; afirst grating that has a grating whose periodic direction is a directionparallel to the first axis, and is placed on the movable body; a secondgrating that has a grating whose periodic direction is a directionparallel to the second axis, and is placed on the movable body; a firstaxis encoder that has a plurality of first heads whose positions aredifferent in a direction parallel to the second axis, and measuresposition information of the movable body in a direction parallel to thefirst axis by the first head that faces the first grating; and a secondaxis encoder that has a plurality of second heads whose positions aredifferent in a direction parallel to the first axis, and measuresposition information of the movable body in a direction parallel to thesecond axis by the second head that faces the second grating, whereinthe plurality of first heads are placed at a distance that is shorterthan a width of the first grating in a direction parallel to the secondaxis, and the plurality of second heads are placed at a distance that isshorter than a width of the second grating in a direction parallel tothe first axis.

With this apparatus, when the movable body is moved, while sequentiallyswitching the plurality of first heads of the first axis encoder, theposition of the movable body in a direction parallel to the first axiscan be measured based on the measurement value of the first head thatfaces the first grating, and in parallel with this operation, whilesequentially switching the plurality of second heads of the second axisencoder, the position of the movable body in a direction parallel to thesecond axis can be measured based on the measurement value of the secondhead that faces the second grating.

According to a fifth aspect of the present invention, there is provideda first exposure apparatus that exposes an object with an energy beamvia an optical system, the apparatus comprising: first and secondmovable bodies that are independently movable within a predeterminedplane; and a detecting unit that has first and second membersrespectively arranged at the first and second movable bodies, anddetects the energy beam via the first and second members.

With this apparatus, since the first and second members are arranged atthe first and second movable bodies respectively, detection of theenergy beam can be performed by the detecting unit while moving thefirst movable body. Further, since only the first member that is part ofthe detecting unit is arranged at the first movable body, the firstmovable body does not increase in size, and therefore the positioncontrollability can be favorably secured.

According to a sixth aspect of the present invention, there is provideda second exposure apparatus that exposes an object with an energy beam,the apparatus comprising: a first movable body that is movable within apredetermined plane, holding the object; a second movable body that ismovable independently from the first movable body within the plane; anda measuring system that includes a first measuring unit that measuresposition information of the first movable body and a second measuringunit that measures position information of the second movable body, ameasurement value of the first measuring unit having short-termstability superior to that of the second measuring unit.

With this apparatus, position information of the first movable body thatmoves within a predetermined plane holding the object is measured by thefirst measuring unit whose measurement value has short-term stabilitysuperior to that of the second measuring unit. Accordingly, positioncontrol of the first movable body that holds the object on which apattern is formed can be stably performed.

According to a seventh aspect of the present invention, there isprovided a third exposure apparatus that exposes an object with anenergy beam, the apparatus comprising: a first movable body which ismovable in first and second directions within a predetermined plane,holding the object, and on which a first grating section that has agrating periodically arrayed in the first direction and a second gratingsection that has a grating periodically arrayed in the second directionare arranged; a second movable body that is movable independently fromthe first movable body within the plane; and a measuring system that hasa first measuring unit that includes an encoder system that measuresposition information of the first movable body by a plurality of headsdifferent two of which face the first and second grating sections, and asecond measuring unit that includes an interferometer that measuresposition information of the second movable body.

With this apparatus, position information of the second movable body ismeasured by the second measuring unit that includes the interferometer,and position information of the first movable body that moves within apredetermined plane holding the object is measured by the firstmeasuring unit that includes the encoder system whose measurement valuehas short-term stability superior to that of the interferometer.Accordingly, position control of the first movable body that holds theobject on which a pattern is formed can be stably performed.

According to an eighth aspect of the present invention, there isprovided a device manufacturing method, comprising: exposing an objectusing any one of the first to third exposure apparatuses of the presentinvention; and developing the exposed object.

According to a ninth aspect of the present invention, there is provideda first pattern forming method of forming a pattern on an object, themethod comprising: a first process of mounting the object on a firstmovable body that moves within a predetermined plane that includes afirst axis and a second axis intersecting the first axis; a secondprocess of measuring position information of a second movable body thatmoves independently from the first movable body within the plane, usinga first measuring system; and a third process of measuring positioninformation of the first movable body using a second measuring systemwhose measurement value has short-term stability superior to that of thefirst measuring system.

With this method, position information of the second movable body ismeasured using the first measuring system, and position information ofthe first movable body that moves within a predetermined plane holdingthe object is measured using the second measuring system whosemeasurement value has short-term stability superior to that of the firstmeasuring system. Accordingly, position control of the first movablebody that holds the object on which a pattern is formed can be stablyperformed.

According to a tenth aspect of the present invention, there is provideda second pattern forming method of forming a pattern on an object byirradiating an energy beam, the method comprising: a process of mountingthe object on a first movable body that moves within a predeterminedplane that includes a first axis and a second axis intersecting thefirst axis; a first measurement process of measuring positioninformation within the plane of a second movable body that movesindependently from the first movable body within the plane, using afirst measuring system that includes an interferometer; and a secondmeasurement process of measuring position information of the firstmovable body within the plane using a second measuring system thatincludes an encoder system that has a plurality of heads, to which firstand second gratings that are placed on the first movable body and havegratings whose periodic directions are directions parallel to the firstand second axes respectively are severally placed facing, and measuresposition information of the first movable body within the plane.

With this method, position information of the second movable body withina predetermined plane is measured using the first measuring system thatincludes the interferometer, and position information of the firstmovable body within the predetermined plane is measured using the secondmeasuring system that includes the encoder system that has a pluralityof heads, to which first and second gratings that are placed on thefirst movable body and have gratings whose periodic directions aredirections parallel to the first and second axes respectively areseverally placed facing, and measures position information of the firstmovable body within the plane. Accordingly, position control of thefirst movable body that holds the object on which a pattern is formed byirradiating an energy beam can be stably performed.

According to an eleventh aspect of the present invention, there isprovided a movable body drive system that drives a movable body thatmoves within a predetermined plane that includes a first axis and asecond axis orthogonal to each other, the system comprising: a firstinterferometer that measures position information of the movable body ina direction parallel to the first axis by irradiating a measurement beamto a reflection surface arranged on the movable body; a secondinterferometer that measures position information of the movable body ina direction parallel to the second axis by irradiating a measurementbeam to a reflection surface arranged on the movable body; a firstgrating that has a grating whose periodic direction is a directionparallel to the first axis, and is placed on the movable body; a firsthead unit that has a plurality of heads whose positions are different ina direction parallel to the second axis and constitutes a first encoderthat measures position information of the movable body in a directionparallel to the first axis by the head that faces the first grating; asecond grating that has a grating whose periodic direction is adirection parallel to the second axis, and is placed on the movablebody; a second head unit that has a plurality of heads whose positionsare different in a direction parallel to the first axis and constitutesa second encoder that measures position information of the movable bodyin a direction parallel to the second axis by the head that faces thesecond grating; an arithmetic processing unit that, while moving themovable body in a direction parallel to the first axis based onmeasurement values of the first and second interferometers, ormeasurement values of the second interferometer and the first head unit,obtains correction information on grating warp of the second grating byperforming a predetermined statistical computation using measurementvalues obtained from the plurality of heads of the second head unit thatare sequentially placed facing the second grating according to themovement and a measurement value of at least one of the firstinterferometer and the first head unit that corresponds to each of themeasurement values; and a controller that performs drive of the movablebody in a direction parallel to the second axis, while correcting themeasurement values obtained from the second head unit based on themeasurement value of at least one of the first interferometer and thefirst head unit and the correction information on grating warp of thesecond grating.

With this system, the arithmetic processing unit obtains correctioninformation used to correct warp of each grating constituting the secondgrating, and the controller performs the drive of the movable body in adirection parallel to the second axis while correcting the measurementvalues obtained from the second head unit based on a measurement valueof one of the first interferometer and the first head unit, and thecorrection information on grating warp of the second grating.Accordingly, the drive of the movable body in a direction parallel tothe second axis can accurately be performed using the encoder that iscomposed of the second grating and the second head unit, without beingaffected by the warp of each grating constituting the second grating.Further, by performing the operations similar to those described abovealso with respect to a direction parallel to the first axis, the driveof the movable body in a direction parallel to the first axis can alsobe performed with good accuracy.

According to a twelfth aspect of the present invention, there isprovided a movable body drive method of moving a movable body that moveswithin a predetermined plane that includes a first axis and a secondaxis orthogonal to each other, the method comprising: a first movementprocess of moving the movable body in a direction parallel to the firstaxis, based on a measurement value of a first interferometer thatmeasures position information of the movable body in a directionparallel to the first axis by irradiating a measurement beam to areflection surface arranged on the movable body, and based on ameasurement value of a second interferometer that measures positioninformation of the movable body in a direction parallel to the secondaxis by irradiating a measurement beam to a reflection surface arrangedon the movable body; a first decision process of deciding correctioninformation on grating warp of a first grating that has a grating whoseperiodic direction is a direction parallel to the second axis and isplaced on the movable body, by performing a predetermined statisticalcomputation using measurement values obtained from a plurality of headsthat are sequentially placed facing the first grating according tomovement of the movable body in the first movement process, and ameasurement value of the first interferometer that corresponds to eachof the measurement values, the plurality of heads being among aplurality of heads whose positions are different in a direction parallelto the first axis and which are included in a first head unit thatconstitutes an encoder that measures position information of the movablebody in a direction parallel to the second axis by irradiating adetection light to the first grating; and a drive process of performingdrive of the movable body in a direction parallel to the second axis,while correcting the measurement values obtained from the first headunit based on a measurement value of the first interferometer and thecorrection information on grating warp of the first grating.

With this method, by the processing in the first movement process andthe first decision process, correction information used to correctgrating warp of the first grating is obtained, and by the processing inthe drive process, the drive of the movable body in a direction parallelto the second axis is performed, while correcting the measurement valuesobtained from the first head unit based on a measurement value of thefirst interferometer and the correction information on grating warp ofthe first grating. Accordingly, the drive of the movable body in adirection parallel to the second axis can be performed with goodaccuracy using the first grating and the first head unit (the encoder),without being affected by grating warp of the first grating. Further, byperforming the operations similar to those described above also withrespect to a direction parallel to the first axis, the drive of themovable body in a direction parallel to the first axis can also beperformed.

According to a thirteenth aspect of the present invention, there isprovided a third pattern forming method, comprising: a process ofmounting an object on a movable body that can move within a movingplane; and a process of driving the movable body using the movable bodydrive method of the present invention for formation of a pattern to theobject.

With this method, a pattern can be formed on the object with goodaccuracy.

Further, in a lithography process, a pattern can be formed on an objectwith good accuracy by forming the pattern on the object using any one ofthe first to third pattern forming methods of the present invention, anda microdevice with higher integration can be manufactured with goodyield by performing processing (such as development, and etching) to theobject on which the pattern has been formed.

Accordingly, it can also be said from a fourteenth aspect that thepresent invention is a device manufacturing method in which any one ofthe first to third pattern forming methods of the present invention isused.

According to a fifteenth aspect of the present invention, there isprovided a first exposure method of exposing an object with an energybeam via an optical system, the method comprising: detecting the energybeam via first and second members by using a detecting unit that has thefirst and second members respectively arranged at first and secondmovable bodies that are independently movable within a predeterminedplane.

With this method, since the first and second members are arranged at thefirst and second movable bodies respectively, detection of the energybeam can be performed by the detecting unit while moving the firstmovable body. Further, since only the first member that is part of thedetecting unit is arranged at the first movable body, the first movablebody does not increase in size, and therefore, the positioncontrollability can favorably be secured.

According to a sixteenth aspect of the present invention, there isprovided a second exposure method of exposing an object with an energybeam, the method comprising: a process of measuring position informationof a first movable body that is movable within a predetermined planeholding the object and of a second movable body that is movableindependently from the first movable body within the plane, using firstand second measuring units, wherein a measurement value of the firstmeasuring unit has short-term stability superior to that of the secondmeasuring unit.

With this method, position information of the first movable body thatmoves within a predetermined plane holding the object can be measured bythe first measuring unit whose measurement value has short-termstability superior to that of the second measuring unit. Accordingly,position control of the first movable body that holds the object onwhich a pattern is formed can be stably performed.

According to a seventeenth aspect of the present invention, there isprovided a third exposure method of exposing an object with an energybeam, the method comprising: a process of measuring position informationof a first movable body, which is movable in first and second directionswithin a predetermined plane holding the object and on which a firstgrating section that has a grating periodically arrayed in the firstdirection and a second grating section that has a grating periodicallyarrayed in the second direction are arranged, by a plurality of heads ofan encoder system comprised in a first measuring unit, different twoheads of which faces the first and second grating sections; and aprocess of measuring position information of a second movable body thatis movable independently from the first movable body within the plane byan interferometer comprised in a second measuring unit.

With this method, position information of the second movable body ismeasured by the second measuring unit that includes the interferometer,and position information of the first movable body that moves within apredetermined plane holding the object is measured by the firstmeasuring unit that includes the encoder system whose measurement valuehas short term stability superior to that of the interferometer.Accordingly, position control of the first movable body that holds theobject on which a pattern is formed can be stably performed.

According to an eighteenth aspect of the present invention, there isprovided a device manufacturing method, comprising: exposing an objectusing any one of the first to third exposure methods of the presentinvention; and developing the exposed object.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings;

FIG. 1 is a view schematically showing the configuration of an exposureapparatus related to an embodiment;

FIG. 2 is a planar view showing a stage unit in FIG. 1;

FIG. 3 is a planar view showing the placement of various measuringapparatuses (such as encoders, alignment systems, a multipoint AFsystem, and Z sensors) that are equipped in the exposure apparatus inFIG. 1;

FIG. 4A is a planar view showing a wafer stage, and FIG. 4B is aschematic side view showing a partial cross section of wafer stage WST;

FIG. 5A is a planar view showing a measurement stage, and FIG. 5B is aschematic side view showing a partial cross section of the measurementstage;

FIG. 6 is a perspective view showing the vicinity of the +X side endportion of X-axis stators 80 and 81 in FIG. 2;

FIGS. 7A to 7D are views used to explain the operations of a stoppermechanism;

FIG. 8 is a block diagram showing the main configuration of a controlsystem of the exposure apparatus related to an embodiment;

FIGS. 9A and 9B are views used to explain position measurement within anXY plane of a wafer table by a plurality of encoders each including aplurality of heads placed in the array arrangement, and the transfer ofmeasurement values between the heads;

FIG. 10A is a view showing an example of a configuration of the encoder,and FIG. 10B is a view showing the case where a laser beam LB having asectional shape that is elongated in a periodic direction of a gratingRG is used as a detection light;

FIG. 11 is a view used to explain grating pitch correction and gratingdeformation correction of scales performed in the exposure apparatusrelated to an embodiment;

FIGS. 12A to 12C are views used to explain wafer alignment performed inthe exposure apparatus related to an embodiment;

FIGS. 13A to 13C are views used to explain simultaneous detection ofmarks on a wafer by a plurality of alignment systems performed whilechanging the Z-position of a wafer table WTB (wafer W);

FIGS. 14A and 14B are views used to explain a baseline measurementoperation of a primary alignment system;

FIGS. 15A and 15B are views to explain a baseline measurement operationof secondary alignment systems performed to a wafer at the head of alot;

FIG. 16 is a view used to explain a baseline check operation of thesecondary alignment systems performed at every wafer replacement;

FIGS. 17A and 17B are views used to explain a position adjustmentoperation of the secondary alignment systems;

FIGS. 18A to 18C are views used to explain focus mapping performed inthe exposure apparatus related to an embodiment;

FIGS. 19A and 19B are views used to explain focus calibration performedin the exposure apparatus related to an embodiment;

FIGS. 20A and 20B are views used to explain offset correction among AFsensors performed in the exposure apparatus related to an embodiment;

FIGS. 21A and 21B are views used to explain traverse-Z-moving correctionperformed in the exposure apparatus related to an embodiment;

FIG. 22 is a view showing a state of the wafer stage and the measurementstage while exposure by a step-and-scan method is being performed to awafer on the wafer stage;

FIG. 23 is a view showing a state of the wafer stage and the measurementstage when exposure to wafer W has ended on the wafer stage WST side;

FIG. 24 is a view showing a state of the wafer stage and the measurementstage right after a state where both stages are separate has beenshifted to a state where both stages are in contact with each other,after exposure ends;

FIG. 25 is a view showing a state of both stages when the measurementstage is moving in a −Y direction and the wafer stage is moving towardan unloading position while keeping a positional relation between thewafer table and a measurement table in a Y-axis direction;

FIG. 26 is a view showing a state of the wafer stage and the measurementstage when the measurement stage has reached a position where a Sec-BCHK(interval) is performed;

FIG. 27 is a view showing a state of the wafer stage and the measurementstage when the wafer stage has moved from the unloading position to aloading position in parallel with the Sec-BCHK (interval) beingperformed;

FIG. 28 is a view showing a state of the wafer stage and the measurementstage when the measurement stage has moved to an optimal scrum waitingposition and a wafer has been loaded on the wafer table;

FIG. 29 is a view showing a state of both stages when the wafer stagehas moved to a position where the Pri-BCHK former processing isperformed while the measurement stage is waiting at the optimal scrumwaiting position;

FIG. 30 is a view showing a state of the wafer stage and the measurementstage when alignment marks arranged in three first alignment shot areasare being simultaneously detected using alignment systems AL1, AL2 ₂ andAL2 ₃;

FIG. 31 is a view showing a state of the wafer stage and the measurementstage when the focus calibration former processing is being performed;

FIG. 32 is a view showing a state of the wafer stage and the measurementstage when alignment marks arranged in five second alignment shot areasare being simultaneously detected using alignment systems AL1 and AL2 ₁to AL2 ₄;

FIG. 33 is a view showing a state of the wafer stage and the measurementstage when at least one of the Pri-BCHK latter processing and the focuscalibration latter processing is being performed;

FIG. 34 is a view showing a state of the wafer stage and the measurementstage when alignment marks arranged in five third alignment shot areasare being simultaneously detected using alignment systems AL1 and AL2 ₁to AL2 ₄;

FIG. 35 is a view showing a state of the wafer stage and the measurementstage when alignment marks arranged in three fourth alignment shot areasare being simultaneously detected using alignment systems AL1, AL2 ₂ andAL2 ₃;

FIG. 36 is a view showing a state of the wafer stage and the measurementstage when the focus mapping has ended;

FIG. 37 is a flowchart used to explain an embodiment of a devicemanufacturing method; and

FIG. 38 is a flowchart used to explain a specific example of step 204 inFIG. 37.

DESCRIPTION OF THE EMBODIMENTS

An embodiment of the present invention will be described below, withreference to FIGS. 1 to 36.

FIG. 1 schematically shows the configuration of an exposure apparatus100 related to an embodiment. Exposure apparatus 100 is a scanningexposure apparatus by a step-and-scan method, that is, a so-calledscanner. As will be described later, in the embodiment, a projectionoptical system PL is arranged, and the following description will bemade assuming that a direction parallel to an optical axis AX ofprojection optical system PL is a Z-axis direction, a direction in whicha reticle and a wafer are relatively scanned within a plane orthogonalto the Z-axis direction is a Y-axis direction and a direction that isorthogonal to a Z-axis and a Y-axis is an X-axis direction, and rotation(tilt) directions around the X-axis, the Y-axis and the Z-axis are θx,θy and θz directions respectively.

Exposure apparatus 100 is equipped with an illumination system 10, areticle stage RST that holds a reticle R that is illuminated by anillumination light for exposure (hereinafter, referred to as“illumination light” or “exposure light”) IL from illumination system10, a projection unit PU that includes projection optical system PL thatprojects illumination light IL emitted from reticle R on a wafer W, astage unit 50 that has a wafer stage WST and a measurement stage MST,their control system, and the like. On wafer stage WST, wafer W ismounted.

Illumination system 10 includes a light source and an illuminationoptical system that has an illuminance uniformity optical systemcontaining an optical integrator and the like, and a reticle blind andthe like (none of which is shown), as is disclosed in, for example,Kokai (Japanese Unexamined Patent Application Publication) No.2001-313250 (the corresponding U.S. Patent Application Publication No.2003/0025890) and the like. In illumination system 10, a slit-shapedillumination area IAR on reticle R that is defined by the reticle blind(masking system) is illuminated by illumination light (exposure light)IL with substantially uniform illuminance. In this case, as illuminationlight IL, an ArF excimer laser light (wavelength: 193 nm) is used as anexample. Further, as the optical integrator, for example, a fly-eyelens, a rod integrator (internal reflection type integrator), adiffraction optical element or the like can be used.

On reticle stage RST, reticle R having a pattern surface (the lowersurface in FIG. 1) on which a circuit pattern and the like are formed isfixed by, for example, vacuum suction. Reticle stage RST is finelydrivable within an XY plane and also drivable at designated scanningvelocity in a scanning direction (which is the Y-axis direction being ahorizontal direction of the page surface of FIG. 1), by a reticle stagedrive system 11 (not shown FIG. 1, refer to FIG. 8) including, forexample, a linear motor or the like.

Position information of reticle stage RST within the moving plane(including rotation information in the θz direction) is constantlydetected at a resolution of, for example, around 0.5 to 1 nm with areticle laser interferometer (hereinafter, referred to as a “reticleinterferometer”) 116 via a movable mirror 15 (in actual, a Y movablemirror (or a retroreflector) having a reflection surface orthogonal tothe Y-axis direction and an X movable mirror having a reflection surfaceorthogonal to the X-axis direction are arranged). The measurement valuesof reticle interferometer 116 are sent to a main controller 20 (notshown in FIG. 1, refer to FIG. 8). Main controller 20 controls theposition (and the velocity) of reticle stage RST by computing theposition of reticle stage RST in the X-axis direction, the Y-axisdirection and the θz direction based on the measurement values ofreticle interferometer 116, and controlling reticle stage drive system11 based on the computation results. Incidentally, instead of movablemirror 15, the end surface of reticle stage RST may be polished in orderto form a reflection surface (corresponding to the reflection surface ofmovable mirror 15). Further, reticle interferometer 116 may be capableof measuring also position information of reticle stage RST in at leastone of the Z-axis, θx and θy directions.

Projection unit PU is placed below reticle stage RST in FIG. 1.Projection unit PU includes a barrel 40 and projection optical system PLhaving a plurality of optical elements that are held in a predeterminedpositional relation within barrel 40. As projection optical system PL,for example, a dioptric system that is composed of a plurality of lenses(lens elements) that are arrayed along an optical axis AX directionparallel to the Z-axis direction is used. Projection optical system PLis, for example, both-side telecentric and has a predeterminedprojection magnification (such as one-quarter, one-fifth or one-eighthtimes). Therefore, when illumination area IAR is illuminated byillumination light IL from illumination system 10, illumination light ILhaving passed through reticle R whose pattern surface is placedsubstantially coincidentally with a first surface (object surface) ofprojection optical system PL forms a reduced image of a circuit pattern(a reduced image of part of a circuit pattern) of reticle R withinillumination area IAR on an area (hereinafter, also referred to as an“exposure area”) IA that is conjugate with illumination area IAR onwafer W, which is placed on a second surface (image plane) side ofprojection optical system PL and whose surface is coated with resist(photosensitive agent), via projection optical system PL (projectionunit PU). Although not shown in the drawing, projection unit PU ismounted on a barrel platform that is supported by three support columnsvia a vibration isolation mechanism. As is disclosed in, for example,the pamphlet of International Publication No. 2006/038952, however,projection unit PU may also be supported in a suspended state withrespect to a main frame member (not shown) that is placed aboveprojection unit PU, or a base member on which reticle stage RST isplaced.

Note that in exposure apparatus 100 of the embodiment, since exposureapplying the liquid immersion method is performed, the aperture on areticle side becomes larger when the numerical aperture NA of projectionoptical system PL substantially increases. Therefore, in a dioptricsystem made up of only lenses, it becomes difficult to satisfy thePetzval condition, which tends to lead to an increase in size of theprojection optical system. In order to avoid such an increase in size ofthe projection optical system, a catadioptric system including mirrorsand lenses may also be used. Further, on wafer W, not onlyphotosensitive layers but also, for example, a protective film (topcoatfilm) or the like that protects the wafer or the photosensitive layersmay be formed.

Further, in exposure apparatus 100 of the embodiment, in order toperform exposure applying the liquid immersion method, a nozzle unit 32that constitutes part of a local liquid immersion unit 8 is arranged soas to enclose the periphery of the lower end portion of barrel 40 thatholds an optical element that is closest to an image plane side (wafer Wside) that constitutes projection optical system PL, which is a lens(hereinafter, also referred to a “tip lens”) 191 in this case. In theembodiment, as is shown in FIG. 1, the lower end surface of nozzle unit32 is set to be substantially flush with the lower end surface of tiplens 191. Further, nozzle unit 32 is equipped with a supply opening anda recovery opening of liquid Lq, a lower surface to which wafer W isplaced facing and at which the recovery opening is arranged, and asupply flow channel and a recovery flow channel that are connected to aliquid supply pipe 31A and a liquid recovery pipe 31B respectively. Asis shown in FIG. 3, liquid supply pipe 31A and liquid recovery pipe 31Bare inclined at an angle of 45 degrees with respect to the X-axisdirection and the Y-axis direction in a planer view (when viewed fromabove) and are symmetrically placed with respect to a straight line LVin the Y-axis direction that passes through optical axis AX ofprojection optical system PL.

One end of a supply pipe (not shown) is connected to liquid supply pipe31A while the other end of the supply pipe is connected to a liquidsupply unit 5 (not shown in FIG. 1, refer to FIG. 8), and one end of arecovery pipe (not shown) is connected to liquid recovery pipe 31B whilethe other end of the recovery pipe is connected to a liquid recoveryunit 6 (not shown in FIG. 1, refer to FIG. 8).

Liquid supply unit 5 includes a liquid tank, a compression pump, atemperature controller, a valve for controlling supply/stop of theliquid to liquid supply pipe 31A, and the like. As the valve, forexample, a flow rate control valve is preferably used so that not onlythe supply/stop of the liquid but also the adjustment of flow rate canbe performed. The temperature controller adjusts the temperature of theliquid within the liquid tank to nearly the same temperature, forexample, as the temperature within the chamber (not shown) where theexposure apparatus is housed. Incidentally, the tank for supplying theliquid, the compression pump, the temperature controller, the valve, andthe like do not all have to be equipped in exposure apparatus 100, andat least part of them can also be substituted by the equipment or thelike available in the plant where exposure apparatus 100 is installed.

Liquid recovery unit 6 includes a liquid tank, a suction pump, a valvefor controlling recovery/stop of the liquid via liquid recovery pipe31B, and the like. As the valve, a flow rate control valve is preferablyused similar to the valve of liquid supply unit 5. Incidentally, thetank for recovering the liquid, the suction pump, the valve, and thelike do not all have to be equipped in exposure apparatus 100, and atleast part of them can also be substituted by the equipment available inthe plant where exposure apparatus 100 is installed.

In the embodiment, as the liquid described above, pure water(hereinafter, it will simply be referred to as “water” besides the casewhen specifying is necessary) that transmits the ArF excimer laser light(light with a wavelength of 193 nm) is to be used. Pure water can beobtained in large quantities at a semiconductor manufacturing plant orthe like without difficulty, and it also has an advantage of having noadverse effect on the photoresist on the wafer, to the optical lenses orthe like.

Refractive index n of the water with respect to the ArF excimer laserlight is around 1.44. In the water the wavelength of illumination lightIL is 193 nm×1/n, shorted to around 134 nm.

Liquid supply unit 5 and liquid recovery unit 6 each have a controller,and the respective controllers are controlled by main controller 20(refer to FIG. 8). According to instructions from main controller 20,the controller of liquid supply unit 5 opens the valve connected toliquid supply pipe 31A to a predetermined degree to supply water to thespace between tip lens 191 and wafer W via liquid supply pipe 31A, thesupply flow channel and the supply opening. Further, when the water issupplied, according to instructions from main controller 20, thecontroller of liquid recovery unit 6 opens the valve connected to liquidrecovery pipe 31B to a predetermined degree to recover the water fromthe space between tip lens 191 and wafer W into liquid recovery unit 6(the liquid tank) via the recovery opening, the recovery flow channeland liquid recovery pipe 31B. During the supply and recovery operations,main controller 20 gives commands to the controllers of liquid supplyunit 5 and liquid recovery unit 6 so that the quantity of water suppliedto the space between tip lens 191 and wafer W constantly equals thequantity of water recovered from the space. Accordingly, a constantquantity of liquid (water) Lq (refer to FIG. 1) is held in the spacebetween tip lens 191 and wafer W. In this case, liquid (water) Lq heldin the space between tip lens 191 and wafer W is constantly replaced.

As is obvious from the above description, in the embodiment, localliquid immersion unit 8 is configured including nozzle unit 32, liquidsupply unit 5, liquid recovery unit 6, liquid supply pipe 31A and liquidrecovery pipe 31B, and the like. Incidentally, part of local liquidimmersion unit 8, for example, at least nozzle unit 32 may also besupported in a suspended state by a main frame (including the barrelplatform) that holds projection unit PU, or may also be arranged atanother frame member that is separate from the main frame. Or, in thecase projection unit PU is supported in a suspended state as isdescribed earlier, nozzle unit 32 may also be supported in a suspendedstate integrally with projection unit PU, but in the embodiment, nozzleunit 32 is arranged on a measurement frame that is supported in asuspended state independently from projection unit PU. In this case,projection unit PU does not have to be supported in a suspended state.

Incidentally, also in the case measurement stage MST is located belowprojection unit PU, the space between a measurement table (to bedescribed later) and tip lens 191 can be filled with water in thesimilar manner to the manner described above.

Incidentally, in the above description, one liquid supply pipe (nozzle)and one liquid recovery pipe (nozzle) are to be arranged as an example.However, the present invention is not limited to this, and aconfiguration having multiple nozzles as disclosed in, for example, thepamphlet of International Publication No. 99/49504, may also beemployed, in the case such arrangement is possible taking intoconsideration a relation with adjacent members. The point is that anyconfiguration may be employed as far as the liquid can be supplied inthe space between an optical member in the lowest end (tip lens) 191constituting projection optical system PL and wafer W. For example, theliquid immersion mechanism disclosed in the pamphlet of InternationalPublication No. 2004/053955, or the liquid immersion mechanism disclosedin the EP Patent Application Publication No. 1 420 298 can also beapplied to the exposure apparatus of the embodiment.

Referring back to FIG. 1, stage unit 50 is equipped with wafer stage WSTand measurement stage MST that are placed above a base board 12, aninterferometer system 118 (refer to FIG. 8) including Y-axisinterferometers 16 and 18 that measure position information of stagesWST and MST, an encoder system (to be described later) that is used formeasuring position information of wafer stage WST on exposure or thelike, a stage drive system 124 (refer to FIG. 8) that drives stages WSTand MST, and the like.

On the bottom surface of each of wafer stage WST and measurement stageMST, a noncontact bearing (not shown), for example, a vacuum preloadtype hydrostatic air bearing (hereinafter, referred to as an “air pad”)is arranged at a plurality of points, and wafer stage WST andmeasurement stage MST are supported in a noncontact manner via aclearance of around several μm above base board 12, by static pressureof pressurized air that is blown out from the air pad toward the uppersurface of base board 12. Further, stages WST and MST are independentlydrivable in two-dimensional directions, which are the Y-axis direction(a horizontal direction of the page surface of FIG. 1) and the X-axisdirection (an orthogonal direction to the page surface of FIG. 1), bystage drive system 124.

To be more specific, as is shown in the planar view in FIG. 2, on afloor surface, a pair of Y-axis stators 86 and 87 extending in theY-axis direction are respectively placed on one side and the other sidein the X-axis direction having base board 12 in between. Y-axis stators86 and 87 are each composed of, for example, a magnetic pole unit thatincorporates a permanent magnet group that is made up of plural pairs ofa north pole magnet and a south pole magnet that are placed at apredetermined distance and alternately along the Y-axis direction. AtY-axis stators 86 and 87, two Y-axis movers 82 and 84, and two Y-axismovers 83 and 85 are respectively arranged in a noncontact engagedstate. In other words, four Y-axis movers 82, 84, 83 and 85 in total arein a state of being inserted in the inner space of Y-axis stator 86 or87 whose XZ sectional surface has a U-like shape, and are severallysupported in a noncontact manner via a clearance of, for example, aroundseveral μm via the air pad (not shown) with respect to correspondingY-axis stator 86 or 87. Each of Y-axis movers 82, 84, 83 and 85 iscomposed of, for example, an armature unit that incorporates armaturecoils placed at a predetermined distance along the Y-axis direction.That is, in the embodiment, Y-axis movers 82 and 84 made up of thearmature units and Y-axis stator 86 made up of the magnetic pole unitconstitute moving coil type Y-axis linear motors respectively.Similarly, Y-axis movers 83 and 85 and Y-axis stator 87 constitutemoving coil type Y-axis linear motors respectively. In the followingdescription, each of the four Y-axis linear motors described above isreferred to as a Y-axis linear motor 82, a Y-axis linear motor 84, aY-axis linear motor 83 and a Y-axis linear motor 85 as needed, using thesame reference codes as their movers 82, 84, 83 and 85.

Movers 82 and 83 of two Y-axis linear motors 82 and 83 out of the fourY-axis linear motors are respectively fixed to one end and the other endin a longitudinal direction of an X-axis stator 80 that extends in theX-axis direction. Further, movers 84 and 85 of the remaining two Y-axislinear motors 84 and 85 are fixed to one end and the other end of anX-axis stator 81 that extends in the X-axis direction. Accordingly,X-axis stators 80 and 81 are driven along the Y-axis by a pair of Y-axislinear motors 82 and 83 and a pair of Y-axis linear motors 84 and 85respectively.

Each of X-axis stators 80 and 81 is composed of, for example, anarmature unit that incorporates armature coils placed at a predetermineddistance along the X-axis direction.

One X-axis stator, X-axis stator 81 is arranged in a state of beinginserted in an opening (not shown) formed at a stage main section 91(not shown in FIG. 2, refer to FIG. 1) that constitutes part of waferstage WST. Inside the opening of stage main section 91, for example, amagnetic pole unit, which has a permanent magnet group that is made upof plural pairs of a north pole magnet and a south pole magnet placed ata predetermined distance and alternately along the X-axis direction, isarranged. This magnetic pole unit and X-axis stator 81 constitute amoving magnet type X-axis linear motor that drives stage main section 91in the X-axis direction. Similarly, the other X-axis stator, X-axisstator 80 is arranged in a state of being inserted in an opening formedat a stage main section 92 that constitutes part of measurement stageMST. Inside the opening of stage main section 92, a magnetic pole unit,which is similar to the magnetic pole unit on the wafer stage WST side(stage main section 91 side), is arranged. This magnetic pole unit andX-axis stator 80 constitute a moving magnet type X-axis linear motorthat drives measurement stage MST in the X-axis direction.

In the embodiment, each of the linear motors described above thatconstitute stage drive system 124 is controlled by main controller 20shown in FIG. 8. Incidentally, each linear motor is not limited toeither one of the moving magnet type or the moving coil type, and thetypes can appropriately be selected as needed.

Incidentally, by making thrust forces severally generated by a pair ofY-axis linear motors 84 and 85 be slightly different, yawing (rotationin the θz direction) of wafer stage WST can be controlled. Further, bymaking thrust forces severally generated by a pair of Y-axis linearmotors 82 and 83 be slightly different, yawing of measurement stage MSTcan be controlled.

Wafer stage WST includes stage main section 91 described above and awafer table WTB that is mounted on stage main section 91 via aZ-leveling mechanism (not shown) (such as a voice coil motor) and isfinely driven relative to stage main section 91 in the Z-axis direction,the θx direction and the θy direction. Incidentally, in FIG. 8, stagedrive system 124 is shown including each of the linear motors and theZ-leveling mechanism described above.

On wafer table WTB, a wafer holder (not shown) that holds wafer W byvacuum suction or the like is arranged. The wafer holder may also beformed integrally with wafer table WTB, but in the embodiment, the waferholder and wafer table WTB are separately configured, and the waferholder is fixed inside a recessed portion of wafer table WTB, forexample, by vacuum suction or the like. Further, on the upper surface ofwafer table WTB, a plate (liquid repellent plate) 28 is arranged, whichhas the surface (liquid repellent surface) substantially flush with thesurface of a wafer mounted on the wafer holder to which liquid repellentprocessing with respect to liquid Lq is performed, has a rectangularouter shape (contour), and has a circular opening that is formed in thecenter portion and is slightly larger than the wafer holder (a mountingarea of the wafer). Plate 28 is made of materials with a low coefficientof thermal expansion, such as glasses or ceramics (such as Zerodur (thebrand name) of Schott AG, Al₂O₃, or TiC), and on the surface of plate28, a liquid repellent film is formed by, for example, fluorine resinmaterials, fluorine series resin materials such aspolytetrafluoroethylene (Teflon (registered trademark)), acrylic resinmaterials, or silicon series resin materials. Further, as is shown in aplaner view of wafer table WTB (wafer stage WST) in FIG. 4A, plate 28has a first liquid repellent area 28 a whose outer shape (contour) isrectangular enclosing a circular opening, and a second liquid repellentarea 28 b that has a rectangular frame (annular) shape placed aroundfirst liquid repellent area 28 a. On first liquid repellent area 28 a,for example, at the time of an exposure operation, at least part of aliquid immersion area 14 that is protruded from the surface of the waferis formed, and on second liquid repellent area 28 b, scales for anencoder system (to be described later) are formed. Incidentally, atleast part of the surface of plate 28 does not have to be flush with thesurface of the wafer, that is, may have a different height from that ofthe surface of the wafer. Further, plate 28 may be a single plate, butin the embodiment, plate 28 is configured by combining a plurality ofplates, for example, first and second liquid repellent plates thatcorrespond to first liquid repellent area 28 a and second liquidrepellent area 28 b respectively. In the embodiment, pure water is usedas liquid Lq as is described above, and therefore, hereinafter firstliquid repellent area 28 a and second liquid repellent area 28 b arealso referred to as first water repellent plate 28 a and second waterrepellent plate 28 b.

In this case, exposure light IL is irradiated to first water repellentplate 28 a on the inner side, while exposure light IL is hardlyirradiated to second water repellent plate 28 b on the outer side.Taking this fact into consideration, in the embodiment, a first waterrepellent area to which water repellent coat having sufficientresistance to exposure light IL (light in a vacuum ultraviolet region,in this case) is applied is formed on the surface of first waterrepellent plate 28 a, and a second water repellent area to which waterrepellent coat having resistance to exposure light IL inferior to thefirst water repellent area is applied is formed on the surface of secondwater repellent plate 28 b. In general, since it is difficult to applywater repellent coat having sufficient resistance to exposure light IL(light in a vacuum ultraviolet region, in this case) to a glass plate,it is effective to separate the water repellent plate into two sectionsin this manner, i.e. first water repellent plate 28 a and second waterrepellent plate 28 b around it. Incidentally, the present invention isnot limited to this, and two types of water repellent coat that havedifferent resistance to exposure light IL may also be applied on theupper surface of the same plate in order to form the first waterrepellent area and the second water repellent area. Further, the samekind of water repellent coat may be applied to the first and secondwater repellent areas. For example, only one water repellent area mayalso be formed on the same plate.

Further, as is obvious from FIG. 4A, at the end portion on the +Y sideof first water repellent plate 28 a, a rectangular cutout is formed inthe center portion in the X-axis direction, and a measurement plate 30is embedded inside the rectangular space (inside the cutout) that isenclosed by the cutout and second water repellent plate 28 b. A fiducialmark FM is formed in the center in the longitudinal direction ofmeasurement plate 30 (on a centerline LL of wafer table WTB), and a pairof aerial image measurement slit patterns (slit-shaped measurementpatterns) SL are formed in the symmetrical placement with respect to thecenter of the fiducial mark on one side and the other side in the X-axisdirection of the fiducial mark. As each of aerial image measurement slitpatterns SL, an L-shaped slit pattern having sides along the Y-axisdirection and X-axis direction, or two linear slit patterns extending inthe X-axis and Y-axis directions respectively can be used, as anexample.

Further, as is shown in FIG. 4B, inside wafer stage WST below each ofaerial image measurement slit patterns SL, an L-shaped housing 36 inwhich an optical system containing an objective lens, a mirror, a relaylens and the like is housed is attached in a partially embedded statepenetrating through part of the inside of wafer table WTB and stage mainsection 91. Housing 36 is arranged in pairs corresponding to the pair ofaerial image measurement slit patterns SL, although omitted in thedrawing.

The optical system inside housing 36 guides illumination light IL thathas been transmitted through aerial image measurement slit pattern SLalong an L-shaped route and emits the light toward a −Y direction.Incidentally, in the following description, the optical system insidehousing 36 is described as a light-transmitting system 36 by using thesame reference code as housing 36 for the sake of convenience.

Moreover, on the upper surface of second water repellent plate 28 b,multiple grating lines are directly formed in a predetermine pitch alongeach of four sides. More specifically, in areas on one side and theother side in the X-axis direction of second water repellent plate 28 b(both sides in the horizontal direction in FIG. 4A), Y scales 39Y₁ and39Y₂ are formed respectively, and Y scales 39Y₁ and 39Y₂ are eachcomposed of a reflective grating (e.g. diffraction grating) having aperiodic direction in the Y-axis direction in which grating lines 38having the longitudinal direction in the X-axis direction are formed ina predetermined pitch along a direction parallel to the Y-axis (Y-axisdirection).

Similarly, in areas on one side and the other side in the Y-axisdirection of second water repellent plate 28 b (both sides in thevertical direction in FIG. 4A), X scales 39X₁ and 39X₂ are formedrespectively, and X scales 39X₁ and 39X₂ are each composed of areflective grating (e.g. diffraction grating) having a periodicdirection in the X-axis direction in which grating lines 37 having thelongitudinal direction in the Y-axis direction are formed in apredetermined pitch along a direction parallel to the X-axis (X-axisdirection). As each of the scales, the scale made up of a reflectivediffraction grating RG (FIG. 10A) that is created by, for example,hologram or the like on the surface of second water repellent plate 28 bis used. In this case, each scale has gratings made up of narrow slits,grooves or the like that are marked at a predetermined distance (pitch)as graduations. The type of diffraction grating used for each scale isnot limited, and not only the diffraction grating made up of grooves orthe like that are mechanically formed, but also, for example, thediffraction grating that is created by exposing interference fringe on aphotosensitive resin may be used. However, each scale is created bymarking the graduations of the diffraction grating, for example, in apitch between 138 nm to 4 μm, for example, a pitch of 1 μm on a thinplate shaped glass. These scales are covered with the liquid repellentfilm (water repellent film) described above. Incidentally, the pitch ofthe grating is shown much wider in FIG. 4A than the actual pitch, forthe sake of convenience. The same is true also in other drawings.

In this manner, in the embodiment, since second water repellent plate 28b itself constitutes the scales, a glass plate with low-thermalexpansion is to be used as second water repellent plate 28 b. However,the present invention is not limited to this, and a scale member made upof a glass plate or the like with low-thermal expansion on which agrating is formed may also be fixed on the upper surface of wafer tableWTB, for example, by a plate spring (or vacuum suction) or the like soas to prevent local shrinkage/expansion. In this case, a water repellentplate to which the same water repellent coat is applied on the entiresurface may be used instead of plate 28. Or, wafer table WTB may also beformed by materials with a low coefficient of thermal expansion, and insuch a case, a pair of Y scales and a pair of X scales may be directlyformed on the upper surface of wafer table WTB.

Mirror finish is severally applied to the −Y end surface and the −X endsurface of wafer table WTB, and a reflection surface 17 a and areflection surface 17 b shown in FIG. 2 are formed. By severallyprojecting an interferometer beam (measurement beam) to reflectionsurface 17 a and reflection surface 17 b and receiving a reflected lightof each beam, Y-axis interferometer 16 and an X-axis interferometer 126(X-axis interferometer 126 is not shown in FIG. 1, refer to FIG. 2) ofinterferometer system 118 (refer to FIG. 8) measure a displacement ofeach reflection surface from a datum position (generally, a fixed mirroris placed on the side surface of projection unit PU, and the surface isused as a datum surface), that is, position information of wafer stageWST within the XY plane, and the measurement values are supplied to maincontroller 20. In the embodiment, as both of Y-axis interferometer 16and X-axis interferometer 126, a multiaxial interferometer having aplurality of optical axes is used, and based on the measurement valuesof Y-axis interferometer 16 and X-axis interferometer 126, maincontroller 20 can measure rotation information in the θx direction (i.e.pitching), rotation information in the θy direction (i.e. rolling), androtation information in the θz direction (i.e. yawing) of wafer tableWTB in addition to the X-position and Y-position of wafer table WTB. Inthe embodiment, however, position information within the XY plane(including the rotation information in the θz direction) of wafer stageWST (wafer table WTB) is mainly measured by an encoder system (to bedescribed later) that includes the Y scales and the X scales describedabove and the like, and the measurement values of interferometers 16 and126 are secondarily used in the cases such as when long-term fluctuationof the measurement values of the encoder system (e.g. due to deformationover time of the scales, or the like) is corrected (calibrated).Further, Y-axis interferometer 16 is used for measuring the Y-positionof wafer table WTB or the like near the unloading position or theloading position (to be described later), for wafer replacement.Further, also in movement of wafer stage WST, for example, between aloading operation and an alignment operation, and/or between an exposureoperation and an unloading operation, measurement information ofinterferometer system 118, that is, at least one of position informationin directions of five degrees of freedom (the X-axis, Y-axis, θx, θy andθz directions) is used. Incidentally, at least part of interferometersystem 118 (such as an optical system) may be arranged at the main framethat holds projection unit PU, or may also be arranged integrally withprojection unit PU that is supported in a suspended state as isdescribed above, but, in the embodiment, interferometer system 118 is tobe arranged at the measurement frame described above.

Incidentally, in the embodiment, wafer stage WST is to include stagemain section 91 that is freely movable within the XY plane and wafertable WTB that is mounted on stage main section 91 and is finelydrivable relative to stage main section 91 in the Z-axis direction, theθx direction and the θy direction. However, the present invention is notlimited to this, and a single stage that is movable in directions of sixdegrees of freedom may also be employed as wafer stage WST as a matterof course. Further, instead of reflection surface 17 a and reflectionsurface 17 b, a movable mirror made up of a planar mirror may also bearranged at wafer table WTB. Moreover, position information of waferstage WST is to be measured using the reflection surface of the fixedmirror arranged at projection unit PU as a datum surface, but theposition where the datum surface is placed is not limited to projectionunit PU, and position information of wafer stage WST does not alwayshave to be measured using the fixed mirror.

Further, in the embodiment, position information of wafer stage WSTmeasured by interferometer system 118 is not to be used in an exposureoperation or an alignment operation (to be described later) but is to bemainly used in a calibration operation of the encoder system (i.e.calibration of measurement values) or the like. However, measurementinformation of interferometer system 118 (i.e. at least one of positioninformation in directions of five degrees of freedom) may also be usedin operations such as the exposure operation and/or the alignmentoperation. In the embodiment, the encoder system measures positioninformation of wafer stage WST in directions of three degrees offreedom, that is, position information in the X-axis, Y-axis and θzdirections. Then, in the exposure operation or the like, out ofmeasurement information of interferometer system 118, only positioninformation related to different directions from measurement directions(the X-axis, Y-axis and θz directions) of position information of waferstage WST by the encoder system, for example, related to the θxdirection and/or the θy direction may also be used. Or, in addition tothe position information related to different directions, positioninformation related to the same directions as the measurement directionsof the encoder system (i.e. at least one of the X-axis, Y-axis and θzdirections) may also be used. Further, interferometer system 118 mayalso be capable of measuring position information of wafer stage WST inthe Z-axis direction. In this case, position information in the Z-axisdirection may be used in the exposure operation or the like.

Measurement stage MST includes stage main section 92 described above anda measurement table MTB mounted on stage main section 92. Measurementtable MTB is mounted on stage main section 92 also via a Z-levelingmechanism (not shown). However, the present invention is not limited tothis, and, for example, measurement stage MST having a so-calledcoarse/fine motion structure in which measurement table MTB isconfigured finely movable with respect to stage main section 92 in theX-axis direction, the Y-axis direction and the θz direction may also beemployed, or the configuration may also be employed in which measurementtable MTB is fixed on stage main section 92 and stage main section 92including measurement table MTB is drivable in directions of six degreesof freedom.

Various types of measurement members are arranged at measurement tableMTB (and stage main section 92). For example, as is shown in FIGS. 2 and5A, measurement members such as an irregular illuminance sensor 94 thathas a pinhole-shaped light-receiving section that receives illuminationlight IL on an image plane of projection optical system PL, an aerialimage measuring instrument 96 that measures an aerial image (projectedimage) of a pattern that is projected by projection optical system PL,and a wavefront aberration measuring instrument 98 by the Shack-Hartmanmethod that is disclosed in, for example, the pamphlet of InternationalPublication No. 03/065428 and the like are employed. As wavefrontaberration measuring instrument 98, the one disclosed in, for example,the pamphlet of International Publication No. 99/60361 (thecorresponding EP Patent Application Publication No. 1079223) can also beused.

As irregular illuminance sensor 94, the configuration similar to the onethat is disclosed in, for example, Kokai (Japanese Unexamined PatentApplication Publication) No. 57-117238 (the corresponding U.S. Pat. No.4,465,368) and the like can be used. Further, as aerial image measuringinstrument 96, the configuration similar to the one that is disclosedin, for example, Kokai (Japanese Unexamined Patent ApplicationPublication) No. 2002-014005 (the corresponding U.S. Patent ApplicationPublication No. 2002/0041377) and the like can be used. Incidentally,three measurement members (94, 96 and 98) are to be arranged atmeasurement stage MST in the embodiment, however, the types and/or thenumber of measurement members are/is not limited to them. As themeasurement members, for example, measurement members such as atransmittance measuring instrument that measures a transmittance ofprojection optical system PL, and/or a measuring instrument thatobserves local liquid immersion unit 8, for example, nozzle unit 32 (ortip lens 191) or the like may also be used. Furthermore, membersdifferent from the measurement members such as a cleaning member thatcleans nozzle unit 32, tip lens 191 or the like may also be mounted onmeasurement stage MST.

In the embodiment, as can be seen from FIG. 5A, the sensors that arefrequently used such as irregular illuminance sensor 94 and aerial imagemeasuring instrument 96 are placed on a centerline CL (Y-axis passingthrough the center) of measurement stage MST. Therefore, in theembodiment, measurement using theses sensors can be performed by movingmeasurement stage MST only in the Y-axis direction without moving themeasurement stage in the X-axis direction.

In addition to each of the sensors described above, an illuminancemonitor that has a light-receiving section having a predetermined areasize that receives illumination light IL on the image plane ofprojection optical system PL may also be employed, which is disclosedin, for example, Kokai (Japanese Unexamined Patent ApplicationPublication) No. 11-016816 (the corresponding U.S. Patent ApplicationPublication No. 2002/0061469) and the like. The illuminance monitor isalso preferably placed on the centerline.

Incidentally, in the embodiment, liquid immersion exposure is performedin which wafer W is exposed with exposure light (illumination light) ILvia projection optical system PL and liquid (water) Lq, and accordinglyirregular illuminance sensor 94 (and the illuminance monitor), aerialimage measuring instrument 96 and wavefront aberration measuringinstrument 98 that are used in measurement using illumination light ILreceive illumination light IL via projection optical system PL andwater. Further, only part of each sensor such as the optical system maybe mounted on measurement table MTB (and stage main section 92), or theentire sensor may be placed on measurement table MTB (and stage mainsection 92).

As is shown in FIG. 5B, a frame-shaped attachment member 42 is fixed tothe end surface on the −Y side of stage main section 92 of measurementstage MST. Further, to the end surface on the −Y side of stage mainsection 92, a pair of photodetection systems 44 are fixed in thevicinity of the center position in the X-axis direction inside anopening of attachment member 42, in the placement capable of facing apair of light-transmitting systems 36 described previously. Each ofphotodetection systems 44 is composed of an optical system such as arelay lens, a light-receiving element such as a photomultiplier tube,and a housing that houses them. As is obvious from FIGS. 4B and 5B andthe description so far, in the embodiment, in a state where wafer stageWST and measurement stage MST are closer together within a predetermineddistance in the Y-axis direction (including a contact state),illumination light IL that has been transmitted through each aerialimage measurement slit pattern SL of measurement plate 30 is guided byeach light-transmitting system 36 and received by the light-receivingelement of each photodetection system 44. That is, measurement plate 30,light-transmitting systems 36 and photodetection systems 44 constitutean aerial image measuring unit 45 (refer to FIG. 8), which is similar tothe one disclosed in Kokai (Japanese Unexamined Patent ApplicationPublication) No. 2002-014005 (the corresponding U.S. Patent ApplicationPublication No. 2002/0041377) referred to previously, and the like.

On attachment member 42, a confidential bar (hereinafter, shortlyreferred to as a “CD bar”) 46 that is made up of a bar-shaped memberhaving a rectangular sectional shape and serves as a reference member isarranged extending in the X-axis direction. CD bar 46 is kinematicallysupported on measurement stage MST by full-kinematic mount structure.

Since CD bar 46 serves as a prototype standard (measurement standard),optical glass ceramics with a low coefficient of thermal expansion, suchas Zerodur (the brand name) of Schott AG are employed as the materials.The flatness degree of the upper surface (the surface) of CD bar 46 isset high to be around the same level as a so-called datum plane plate.Further, as is shown in FIG. 5A, a reference grating (e.g. diffractiongrating) 52 whose periodic direction is the Y-axis direction isrespectively formed in the vicinity of the end portions on one side andthe other side in the longitudinal direction of CD bar 46. The pair ofreference gratings 52 are formed apart at a predetermined distance(which is to be “L”) in the symmetrical placement with respect to thecenter in the X-axis direction of CD bar 46, that is, centerline CLdescribed above.

Further, on the upper surface of CD bar 46, a plurality of referencemarks M are formed in the placement as shown in FIG. 5A. The pluralityof reference marks M are formed in three-row arrays in the Y-axisdirection in the same pitch, and the array of each row is formed beingshifted from each other by a predetermined distance in the X-axisdirection. As each of reference marks M, a two-dimensional mark having asize that can be detected by a primary alignment system and secondaryalignment systems (to be described later) is used. Reference mark M mayalso be different in shape (constitution) from fiducial mark FM, but inthe embodiment, reference mark M and fiducial mark FM have the sameconstitution and also they have the same constitution with that of analignment mark of wafer W. Incidentally, in the embodiment, the surfaceof CD bar 46 and the surface of measurement table MTB (which may includethe measurement members described above) are also covered with a liquidrepellent film (water repellent film) severally.

Also on the +Y end surface and the −X end surface of measurement tableMTB, reflection surfaces 19 a and 19 b are formed similar to wafer tableWTB as described above (refer to FIGS. 2 and 5A). By projecting aninterferometer beam (measurement beam), as is shown in FIG. 2, toreflection surfaces 19 a and 19 b and receiving a reflected light ofeach interferometer beam, Y-axis interferometer 18 and an X-axisinterferometer 130 (X-axis interferometer 130 is not shown in FIG. 1,refer to FIG. 2) of interferometer system 118 (refer to FIG. 8) measurea displacement of each reflection surface from a datum position, thatis, position information of measurement stage MST (e.g. including atleast position information in the X-axis and Y-axis directions androtation information in the θz direction), and the measurement valuesare supplied to main controller 20.

Meanwhile, as is shown in FIG. 2, stopper mechanisms 48A and 48B arearranged at X-axis stator 81 and X-axis stator 80. As is shown in FIG. 6that shows the vicinity of the +X side end portion of X-axis stators 80and 81 in a perspective view, stopper mechanism 48A includes a shockabsorber 47A serving as a buffer unit that is arranged at X-axis stator81 and made up of, for example, an oil damper, and a shutter 49Aarranged at a position (the end surface on the −Y side of the +X endportion) on X-axis stator 80 that faces shock absorber 47A. At theposition on X-axis stator 80 that faces shock absorber 47A, an opening51A is formed.

As is shown in FIG. 6, shutter 49A is drivable in directions of arrows Aand A′ (Z-axis direction) by a drive mechanism 34A that is arranged onthe −Y side of opening 51A formed in X-axis stator 80 and includes, forexample, an air cylinder and the like. Accordingly, shutter 49A can makeopening 51A be in an opened state or a closed state. The opened/closedstate of opening 51A by shutter 49A is detected by an opening/closingsensor 101 (not shown in FIG. 6, refer to FIG. 8) that is arranged inthe vicinity of shutter 49A, and the detection results are sent to maincontroller 20.

Stopper mechanism 48B has the configuration similar to stopper mechanism48A. In other words, as is shown in FIG. 2, stopper mechanism 48Bincludes a shock absorber 47B that is arranged in the vicinity of the −Xend portion of X-axis stator 81, and a shutter 49B arranged at aposition on X-axis stator 80 that faces shock absorber 47B. Further, atthe +Y side portion of shutter 49B of X-axis stator 80, an opening 51Bis formed.

Herein, the operations of stopper mechanisms 48A and 48B will beexplained based on FIGS. 7A to 7D, focusing on stopper mechanism 48A asa representative.

In the case shutter 49A is in a state of closing opening 51A as is shownin FIG. 7A, even when X-axis stator 81 and X-axis stator 80 come closetogether as is shown in FIG. 7B, X-axis stators 81 and 80 cannot comeany closer by shock absorber 47A and shutter 49A coming into contactwith (contacting) each other. In this case, the configuration isemployed in which wafer table WTB and measurement table MTB do not comeinto contact with each other even in the case where a head section 104 dfixed to a tip of a piston rod 104 a of shock absorber 47A moves to themost −Y side (i.e. in the case where a spring (not shown) of shockabsorber 47A contracts most, and the overall length becomes shortest) asis shown in FIG. 7B.

On the other hand, when shutter 49A is driven downward via drivemechanism 34A as is shown in FIG. 7C, opening 51A is in an opened state.In this case, when X-axis stators 81 and 80 come close to each other, atleast part of a tip portion of piston rod 104 a of shock absorber 47Acan be inserted into opening 51A as is shown in FIG. 7D, which makes itpossible to make X-axis stators 81 and 80 come closer to each other thanthe state shown in FIG. 7B. In such a state where X-axis stators 81 and80 are closest to each other, wafer table WTB and measurement table MTB(CD bar 46) can be made to come into contact with each other (or, tocome closer together at a distance of around 300 μm) (refer to FIG. 14Band the like).

As is shown in FIG. 7D, the depth of opening 51A may be set so that agap is formed between shock absorber 47A and a termination portion (aportion corresponding to a bottom) of opening 51A even in a state whereX-axis stators 81 and 80 are closest to each other, or may be set sothat head section 104 d of piston rod 104 a of shock absorber 47Atouches the termination portion. Further, in order to prevent shockabsorber 47A and a wall portion of opening 51A from coming into contactwith each other even in the case X-axis stators 81 and 80 relativelymove in the X-axis direction, a width of the opening portion may also beset in advance in accordance with a quantity of the relative movement.

Incidentally, in the embodiment, a pair of stopper mechanism 48A and 48Bare to be arranged at X-axis stator 81 and X-axis stator 80. However,only one of stopper mechanisms 48A and 48B may also be arranged, or astopper mechanism similar to the one described above may also bearranged at wafer stage WST and measurement stage MST.

Referring back to FIG. 2, a clearance detection sensor 43A and acollision detection sensor 43B are arranged at the +X end portion ofX-axis stator 80, and a plate-shaped member 41A that is elongate in theY-axis direction is arranged protruding to the +Y side at the +X endportion of X-axis stator 81. Further, as is shown in FIG. 2, a clearancedetection sensor 43C and a collision detection sensor 43D are arrangedat the −X end portion of X-axis stator 80, and a plate-shaped member 41Bthat is elongate in the Y-axis direction is arranged protruding to the+Y side at the −X end portion of X-axis stator 81.

Clearance detection sensor 43A is composed of, for example, atransmissive photosensor (e.g. LED-PTr transmissive photosensor), andincludes a fixed member 142 having a U-shape, and an light-emittingsection 144A and a light-receiving section 144B that are respectivelyarranged on a pair of surfaces facing each other of fixed member 142, asis shown in FIG. 6. With clearance detection sensor 43A, in the caseX-axis stator 80 and X-axis stator 81 come close further from the stateof FIG. 6, plate-shaped member 41A comes between light-receiving section144B and light-emitting section 144A and the light from light-emittingsection 144A is intercepted by a lower half portion of plate-shapedmember 41A, and a light quantity received by light-receiving section144B gradually decreases and the output current gradually becomessmaller. Accordingly, main controller 20 can detect that the clearancebetween X-axis stators 80 and 81 becomes equal to or less than apredetermined distance by detecting the output current.

As is shown in FIG. 6, collision detection sensor 43B includes a fixedmember 143 having a U-shape, and an light-emitting section 145A and alight-receiving section 145B that are respectively arranged on a pair ofsurfaces facing each other of fixed member 143. In this case, as isshown in FIG. 6, light-emitting section 145A is placed at a slightlyhigher position than light-emitting section 144A of clearance detectionsensor 43A, and light-receiving section 145B is placed at a slightlyhigher position than light-receiving section 144B of clearance detectionsensor 43A so as to correspond to light-emitting section 145A.

With collision detection sensor 43B, at the stage where X-axis stators80 and 81 further come close to each other and wafer table WTB and CDbar 46 (measurement table MTB) come into contact with each other (or atthe stage where wafer table WTB and CD bar 46 (measurement table MTB)come closer together at a distance of around 300 μm), the position ofthe upper half portion of plate-shaped member 41A is set betweenlight-emitting section 145A and light-receiving section 145B, andtherefore the light from light-emitting section 145A is not incident onlight-receiving section 145B. Accordingly, main controller 20 can detectthat both tables come into contact with each other (or come closertogether at a distance of around 300 μm) by detecting the output currentfrom light-receiving section 145B becoming zero.

Note that clearance detection sensor 43C and collision detection sensor43D that are arranged in the vicinity of the −X end portion of X-axisstator 80 are also configured similar to clearance detection sensor 43Aand collision detection sensor 43B described above, and plate-shapedmember 41B is also configured similar to plate-shaped member 41Adescribed above.

In exposure apparatus 100 of the embodiment, in actual, a primaryalignment system AL1 is placed on straight line LV passing through thecenter of projection unit PU (optical axis AX of projection opticalsystem PL, which also coincides with the center of exposure area IA inthe embodiment) and being parallel to the Y-axis, and has a detectioncenter at a position that is spaced apart from the optical axis at apredetermined distance on the −Y side as is shown in FIG. 3, althoughomitted in FIG. 1 from the viewpoint of avoiding intricacy of thedrawing. Primary alignment system AL1 is fixed to the lower surface of amain frame (not shown) via a support member 54. On one side and theother side in the X-axis direction with primary alignment system AL1 inbetween, secondary alignment systems AL2 ₁ and AL2 ₂, and AL2 ₃ and AL2₄ whose detection centers are substantially symmetrically placed withrespect to straight line LV are severally arranged. That is, fivealignment systems AL1 and AL2 ₁ to AL2 ₄ are placed so that theirdetection centers are placed at different positions in the X-axisdirection, that is, placed along the X-axis direction.

As is representatively shown by secondary alignment system AL2 ₄, eachsecondary alignment system AL2 _(n) (n=1 to 4) is fixed to a tip(turning end) of an arm 56 _(n) (n=1 to 4) that can turn around arotation center O as the center in a predetermined angle range inclockwise and anticlockwise directions in FIG. 3. In the embodiment, apartial section of each secondary alignment system AL2 _(n) (e.g.including at least an optical system that irradiates an alignment lightto a detection area and also leads the light that is generated from asubject mark within the detection area to a light-receiving element) isfixed to arm 56 _(n) and the remaining section is arranged at the mainframe that holds projection unit PU. The X-positions of secondaryalignment systems AL2 ₁, AL2 ₂, AL2 ₃ and AL2 ₄ are severally adjustedby turning around rotation center O as the center. In other words, thedetection areas (or the detection centers) of secondary alignmentsystems AL2 ₁, AL2 ₂, AL2 ₃ and AL2 ₄ are independently movable in theX-axis direction. Accordingly, the relative positions of the detectionareas of primary alignment system AL1 and secondary alignment systemsAL2 ₁, AL2 ₂, AL2 ₃ and AL2 ₄ are adjustable in the X-axis direction.Incidentally, in the embodiment, the X-positions of secondary alignmentsystems AL2 ₁, AL2 ₂, AL2 ₃ and AL2 ₄ are to be adjusted by the turningof the arms. However, the present invention is not limited to this, anda drive mechanism that drives secondary alignment systems AL2 ₁, AL2 ₂,AL2 ₃ and AL2 ₄ back and forth in the X-axis direction may also bearranged. Further, at least one of secondary alignment systems AL2 ₁,AL2 ₂, AL2 ₃ and AL2 ₄ may be movable not only in the X-axis directionbut also in the Y-axis direction. Incidentally, since part of eachsecondary alignment system AL2 _(n) is moved by arm 56 _(n), positioninformation of the part that is fixed to arm 56 _(n) is measurable by asensor (not shown) such as an interferometer, or an encoder. The sensormay only measure position information in the X-axis direction ofsecondary alignment system AL2 _(n), or may be capable of measuringposition information in another direction, for example, the Y-axisdirection and/or the rotation direction (including at least one of theθx and θy directions).

On the upper surface of each arm 56 _(n), a vacuum pad 58 _(n) (n=1 to4) that is composed of a differential evacuation type air bearing isarranged. Further, arm 56 _(n) can be turned by a rotation drivemechanism 60 _(n) (n=1 to 4, not shown in FIG. 3, refer to FIG. 8) thatincludes, for example, a motor or the like, in response to instructionsof main controller 20. Main controller 20 activates each vacuum pad 58_(n) to fix each arm 56 _(n) to a main frame (not shown) by suctionafter rotation adjustment of arm 56 _(n). Thus, the state of each arm 56_(n) after rotation angle adjustment, that is, a desired positionalrelation between primary alignment system AL1 and four secondaryalignment systems AL2 ₁ to AL2 ₄ is maintained. Incidentally, specificrotation adjustment of each arm, that is, an adjusting method ofrelative positions of four secondary alignment systems AL2 ₁ to AL2 ₄with respect to primary alignment system AL1 will be described later.

Incidentally, in the case a portion of the main frame facing arm 56 _(n)is a magnetic body, an electromagnet may also be employed instead ofvacuum pad 58.

In the embodiment, as each of primary alignment system AL1 and foursecondary alignment systems AL2 ₁ to AL2 ₄, for example, an FIA (FieldImage Alignment) system by an image processing method is used thatirradiates a broadband detection beam that does not expose resist on awafer to a subject mark, and picks up an image of the subject markformed on a light-receiving plane by the reflected light from thesubject mark and an image of an index (an index pattern on an indexplate arranged within each alignment system) (not shown), using animaging device (such as CCD), and then outputs their imaging signals.The imaging signal from each of primary alignment system AL1 and foursecondary alignment systems AL2 ₁ to AL2 ₄ is supplied to maincontroller 20 in FIG. 8.

Incidentally, each of the alignment systems described above is notlimited to the FIA system, and an alignment sensor, which irradiates acoherent detection light to a subject mark and detects a scattered lightor a diffracted light generated from the subject mark or makes twodiffracted lights (e.g. diffracted lights of the same order ordiffracted lights being diffracted in the same direction) generated fromthe subject mark interfere and detects an interference light, cannaturally be used alone or in combination as needed. Further, fivealignment systems AL1 and AL2 ₁ to AL2 ₄ are to be arranged in theembodiment. However, the number of alignment systems is not limited tofive, but may be the number equal to or more than two and equal to orless than four, or may be the number equal to or more than six, or maybe the even number, not the odd number. Moreover, in the embodiment,five alignment systems AL1 and AL2 ₁ to AL2 ₄ are to be fixed to thelower surface of the main frame that holds projection unit PU, viasupport member 54. However, the present invention is not limited tothis, and for example, the five alignment systems may also be arrangedon the measurement frame described earlier.

In exposure apparatus 100 of the embodiment, as is shown in FIG. 3, fourhead units 62A to 62D of the encoder system are placed in a state ofsurrounding nozzle unit 32 on all four sides. In actual, head units 62Ato 62D are fixed to the foregoing main frame that holds projection unitPU in a suspended state via a support member, although omitted in thedrawings such as FIG. 3 from the viewpoint of avoiding intricacy of thedrawings. Incidentally, for example, in the case projection unit PU issupported in a suspended state, head units 62A to 62D may be supportedin a suspended state integrally with projection unit PU, or may bearranged at the measurement frame described above.

Head units 62A and 62C are respectively placed on the +X side and −Xside of projection unit PU having the longitudinal direction in theX-axis direction, and are also placed apart at the substantially samedistance from optical axis AX of projection optical system PLsymmetrically with respect to optical axis AX of projection opticalsystem PL. Further, head units 62B and 62D are respectively placed onthe +Y side and −Y side of projection unit PU having the longitudinaldirection in the Y-axis direction and are also placed apart at thesubstantially same distance from optical axis AX of projection opticalsystem PL.

As is shown in FIG. 3, head units 62A and 62C are each equipped with aplurality of (six in this case) Y heads 64 that are placed at apredetermined distance on a straight line LH that passes through opticalaxis AX of projection optical system PL and is parallel to the X-axis,along the X-axis direction. Head unit 62A constitutes a multiple-lens(six-lens in this case) Y linear encoder (hereinafter, shortly referredto as a “Y encoder” or an “encoder” as needed) 70A (refer to FIG. 8)that measures the position in the Y-axis direction (the Y-position) ofwafer stage WST (wafer table WTB) using Y scale 39Y₁ described above.Similarly, head unit 62C constitutes a multiple-lens (six-lens, in thiscase) Y linear encoder 70C (refer to FIG. 8) that measures theY-position of wafer stage WST (wafer table WTB) using Y scale 39Y₂described above. In this case, a distance between adjacent Y heads 64(i.e. measurement beams) equipped in head units 62A and 62C is setshorter than a width in the X-axis direction of Y scales 39Y₁ and 39Y₂(to be more accurate, a length of grating line 38). Further, out of aplurality of Y heads 64 that are equipped in each of head units 62A and62C, Y head 64 located innermost is fixed to the lower end portion ofbarrel 40 of projection optical system PL (to be more accurate, to theside of nozzle unit 32 enclosing tip lens 191) so as to be placed asclose as possible to the optical axis of projection optical system PL.

As is shown in FIG. 3, head unit 62B is equipped with a plurality of(seven in this case) X heads 66 that are placed on straight line LV at apredetermined distance along the Y-axis direction. Further, head unit62D is equipped with a plurality of (eleven in this case, out of elevenX heads, however, three X heads that overlap primary alignment systemAL1 are not shown in FIG. 3) X heads 66 that are placed on straight lineLV at a predetermined distance. Head unit 62B constitutes amultiple-lens (seven-lens, in this case) X linear encoder (hereinafter,shortly referred to as an “X encoder” or an “encoder” as needed) 70B(refer to FIG. 8) that measures the position in the X-axis direction(the X-position) of wafer stage WST (wafer table WTB) using X scale 39X₁described above. Further, head unit 62D constitutes a multiple-lens(eleven-lens, in this case) X linear encoder 70D (refer to FIG. 8) thatmeasures the X-position of wafer stage WST (wafer table WTB) using Xscale 39X₂ described above. Further, in the embodiment, for example, atthe time of alignment (to be described later) or the like, two X heads66 out of eleven X heads 66 that are equipped in head unit 62Dsimultaneously face X scale 39X₁ and X scale 39X₂ respectively in somecases. In these cases, X scale 39X₁ and X head 66 facing X scale 39X₁constitute X linear encoder 70B, and X scale 39X₂ and X head 66 facing Xscale 39X₂ constitute X linear encoder 70D.

Herein, some of eleven X heads 66, in this case, three X heads areattached below support member 54 of primary alignment system AL1.Further, a distance between adjacent X heads 66 (i.e. measurement beams)that are equipped in each of head units 62B and 62D is set shorter thana width in the Y-axis direction of X scales 39X₁ and 39X₂ (to be moreaccurate, a length of grating line 37). Further, X head 66 locatedinnermost out of a plurality of X heads 66 that are quipped in each ofhead units 62B and 62D is fixed to the lower end portion of the barrelof projection optical system PL (to be more accurate, to the side ofnozzle unit 32 enclosing tip lens 191) so as to be placed as close aspossible to the optical axis of projection optical system PL.

Moreover, on the −X side of secondary alignment system AL2 ₁ and on the+X side of secondary alignment system AL2 ₄, Y heads 64Y₁ and 64Y₂ arerespectively arranged, whose detection points are placed on a straightline parallel to the X-axis that passes through the detection center ofprimary alignment system AL1 and are substantially symmetrically placedwith respect to the detection center. The distance between Y heads 64Y₁and 64Y₂ is set substantially equal to distance L described previously.Y heads 64Y₁ and 64Y₂ face Y scales 39Y₂ and 39Y₁ respectively in astate where the center of wafer W on wafer stage WST is on straight lineLV as shown in FIG. 3. On an alignment operation (to be described later)or the like, Y scales 39Y₂ and 39Y₁ are placed facing Y heads 64Y₁ and64Y₂ respectively, and the Y-position (and the θz rotation) of waferstage WST is measured by Y heads 64Y₁ and 64Y₂ (i.e. Y encoders 70C and70A composed of Y heads 64Y₁ and 64Y₂).

Further, in the embodiment, at the time of baseline measurement of thesecondary alignment systems (to be described later) or the like, a pairof reference gratings 52 of CD bar 46 face Y heads 64Y₁ and 64Y₂respectively, and the Y-position of CD bar 46 is measured at theposition of each of reference gratings 52 by Y heads 64Y₁ and 64Y₂ andfacing reference gratings 52. In the following description, encodersthat are composed of Y heads 64Y₁ and 64Y₂ facing reference gratings 52respectively are referred to as Y-axis linear encoders 70E and 70F(refer to FIG. 8).

The measurement values of six linear encoders 70A to 70F are supplied tomain controller 20, and main controller 20 controls the position withinthe XY plane of wafer table WTB based on the measurement values oflinear encoders 70A to 70D, and also controls the rotation in the θzdirection of CD bar 46 based on the measurement values of linearencoders 70E and 70F.

As is shown in FIG. 3, in exposure apparatus 100 of the embodiment, amultipoint focal position detecting system (hereinafter, shortlyreferred to as a “multipoint AF system”) by an oblique incident methodis arranged, which is composed of an irradiation system 90 a and aphotodetection system 90 b, and has the configuration similar to the onedisclosed in, for example, Kokai (Japanese Unexamined Patent ApplicationPublication) No. 06-283403 (the corresponding U.S. Pat. No. 5,448,332)and the like. In the embodiment, as an example, irradiation system 90 ais placed on the −Y side of the −X end portion of head unit 62C andphotodetection system 90 b is placed on the −Y side of the +X endportion of head unit 62A in a state of opposing irradiation system 90 a.

A plurality of detection points of the multipoint AF system (90 a, 90 b)are placed at a predetermined distance along the X-axis direction on thesurface to be detected. In the embodiment, the plurality of detectionpoints are placed, for example, in the arrangement of a row matrixhaving one row and M columns (M is a total number of detection points)or having two rows and N columns (N is a half of a total number ofdetection points). In FIG. 3, the plurality of detection points to whicha detection beam is severally irradiated are not individually shown, butare shown as an elongate detection area AF that extends in the X-axisdirection between irradiation system 90 a and photodetection system 90b. Since the length of detection area AF in the X-axis direction is setto around the same as the diameter of wafer W, position information(surface position information) in the Z-axis direction across the entiresurface of wafer W can be measured by only scanning wafer W in theY-axis direction once. Further, since detection area AF is placedbetween liquid immersion area 14 (exposure area IA) and the detectionareas of the alignment systems (AL1, AL2 ₁, AL2 ₂, AL2 ₃ and AL2 ₄) inthe Y-axis direction, the detection operations of the multipoint AFsystem and the alignment systems can be performed in parallel. Themultipoint AF system may also be arranged on the main frame that holdsprojection unit PU or the like, but is to be arranged on the measurementframe described earlier in the embodiment.

Incidentally, the plurality of detection points are to be placed in onerow and M columns, or two rows and N columns, but the number(s) of rowsand/or columns is/are not limited to these numbers. However, in the casethe number of rows is two or more, the positions in the X-axis directionof detection points are preferably made to be different even between thedifferent rows. Moreover, the plurality of detection points are to beplaced along the X-axis direction. However, the present invention is notlimited to this, and all of or some of the plurality of detection pointsmay also be placed at different positions in the Y-axis direction. Forexample, the plurality of detection points may also be placed along adirection that intersects both of the X-axis and the Y-axis. That is,the positions of the plurality of detection points only have to bedifferent at least in the X-axis direction. Further, a detection beam isto be irradiated to the plurality of detection points in the embodiment,but a detection beam may also be irradiated to, for example, the entirearea of detection area AF. Furthermore, the length of detection area AFin the X-axis direction does not have to be nearly the same as thediameter of wafer W.

In exposure apparatus 100 of the embodiment, in the vicinity ofdetection points located at both ends out of a plurality of detectionpoints of the multipoint AF system, that is, in the vicinity of both endportions of detection area AF, one each pair of surface position sensorsfor Z position measurement (hereinafter, shortly referred to as “Zsensors”), that is, a pair of Z sensors 72 a and 72 b and a pair of Zsensors 72 c and 72 d are arranged in the symmetrical placement withrespect to straight line LV. Z sensors 72 a to 72 d are fixed to thelower surface of a main frame (not shown). As Z sensors 72 a to 72 d, asensor that irradiates a light to wafer table WTB from above, receivesthe reflected light and measures position information of the wafer tableWTB surface in the Z-axis direction orthogonal to the XY plane, as anexample, an optical displacement sensor (sensor by a CD pickup method),which has the configuration like an optical pickup used in a CD driveunit, is used. Incidentally, Z sensors 72 a to 72 d may also be arrangedon the measurement frame described above or the like.

Moreover, head unit 62C is equipped with a plurality of (six each,twelve in total, in this case) Z sensors 74 _(i,j) (i=1, 2, j=1, 2, . .. , 6) that are placed at a predetermined distance, along each of twostraight lines that are located on one side and the other side havingstraight line LH in between in the X-axis direction that connects aplurality of Y heads 64 and are parallel to straight line LH. In thiscase, Z sensors 74 _(1,j) and 74 _(2,j) making a pair are placedsymmetrically with respect to straight line LH. Furthermore, pluralpairs (six pairs, in this case) of Z sensors 74 _(1,j) and 74 _(2,j) anda plurality of Y heads 64 are placed alternately in the X-axisdirection. As each Z sensor 74 _(i,j), for example, a sensor by a CDpickup method similar to Z sensors 72 a to 72 d is used.

Herein, a distance between each pair of Z sensors 74 _(1,j) and 74_(2,j) that are located symmetrically with respect to straight line LHis set to be the same distance as a distance between Z sensors 74 c and74 d. Further, a pair of Z sensors 74 _(1,4) and 74 _(2,4) are locatedon the same straight line parallel to the Y-axis direction as Z sensors72 a and 72 b.

Further, head unit 62A is equipped with a plurality of (twelve in thiscase) Z sensors 76 _(p,q) (p=1, 2 and q=1, 2, . . . , 6) that are placedsymmetrically to a plurality of Z sensors 74 _(i,j) with respect tostraight line LV. As each Z sensor 76 _(p,q), a sensor by a CD pickupmethod similar to Z sensors 72 a to 72 d is used, for example. Further,a pair of Z sensors 76 _(1,3) and 76 _(2,3) are located on the samestraight line in the Y-axis direction as Z sensors 72 c and 72 d.

Incidentally, in FIG. 3, measurement stage MST is omitted and a liquidimmersion area that is formed by water Lq held in the space betweenmeasurement stage MST and tip lens 191 is shown by a reference code 14.Further, in FIG. 3, a reference code 78 indicates a localair-conditioning system that blows dry air whose temperature is adjustedto a predetermined temperature to the vicinity of a beam path of themultipoint AF system (90 a, 90 b) by, for example, downflow as isindicated by outline arrows in FIG. 3. Further, a reference code UPindicates an unloading position where a wafer on wafer table WTB isunloaded, and a reference code LP indicates a loading position where awafer is loaded on wafer table WTB. In the embodiment, unloadingposition UP and loading position LP are set symmetrically with respectto straight line LV. Incidentally, unloading position UP and loadingposition LP may be the same position.

FIG. 8 shows the main configuration of the control system of exposureapparatus 100. The control system is mainly configured of maincontroller 20 composed of a microcomputer (or workstation) that performsoverall control of the entire apparatus. Incidentally, in FIG. 8,various sensors such as irregular illuminance sensor 94, aerial imagemeasuring instrument 96 and wavefront aberration measuring instrument 98that are arranged at measurement stage MST are collectively shown as asensor group 99.

In exposure apparatus 100 of the embodiment having the configurationdescribed above, since the placement of X scales and Y scales on wafertable WTB as described above and the placement of X heads and Y heads asdescribed above are employed, X scales 39X₁ and 39X₂ and head units 62Band 62D (X heads 66) respectively face each other, and Y scales 39Y₁ and39Y₂ and head units 62A and 62C (Y heads 64) or Y heads 64 y ₁ and 64 y₂ respectively face each other without fail in an effective stroke rangeof wafer stage WST (i.e. a range in which wafer stage WST moves for thealignment and the exposure operation, in the embodiment), as isexemplified in the drawings such as FIGS. 9A and 9B. Incidentally, inFIGS. 9A and 9B, the heads that face the corresponding X scales or Yscales are indicated by being circled.

Therefore, in the effective stroke range of wafer stage WST describedabove, main controller 20 can control position information (includingrotation information in the θz direction) within the XY plane of waferstage WST with high precision by controlling each motor constitutingstage drive system 124, based on at least three measurement values ofencoders 70A to 70D. Since the influence of air fluctuations that themeasurement values of encoders 70A to 70D receive is small enough to beignored when comparing with the interferometer, the short-term stabilityof the measurement values that is affected by air fluctuations isremarkably better than that of the interferometer. Incidentally, in theembodiment, the sizes (e.g. the number of heads and/or the distancebetween the heads) of head units 62B, 62D, 62A and 62C are set inaccordance with the effective stork range of wafer stage WST and thesizes (i.e. the formation range of diffraction gratings) of the scales.Accordingly, in the effective stroke range of wafer stage WST, all offour scales 39X₁, 39X₂, 39Y₁ and 39Y₂ face head units 62B, 62D, 62A and62C respectively, but all the four scales do not have to face thecorresponding head units. For example, one of X scales 39X₁ and 39X₂and/or one of Y scales 39Y₁ and 39Y₂ does/do not have to face the headunit. In the case one of X scales 39X₁ and 39X₂ or one of Y scales 39Y₁and 39Y₂ does not face the head unit, three scales face the head unitsin the effective stroke range of wafer stage WST, and therefore,position information of wafer stage WST in the X-axis, Y-axis and θzdirections can constantly be measured. Further, in the case one of Xscales 39X₁ and 39X₂ and one of Y scales 39Y₁ and 39Y₂ do not face thehead units, two scales face the head units in the effective stroke rangeof wafer stage WST, and therefore, position information of wafer stageWST in the θz direction cannot constantly be measured, but positioninformation in the X-axis and Y-axis directions can constantly bemeasured. In this case, position control of wafer stage WST may also beperformed using position information in the θz direction of wafer stageWST measured by interferometer system 118 in combination.

Further, when wafer stage WST is driven in the X-axis direction asindicated by an outline arrow in FIG. 9A, Y head 64 that measures theposition in the Y-axis direction of wafer stage WST is sequentiallyswitched to adjacent Y head 64 as indicated by arrows e₁ and e₂ in thedrawing. For example, Y head 64 circled by a solid line is switched to Yhead 64 circled by a dotted line. Therefore, the measurement values aretransferred before and after the switching. In other words, in theembodiment, in order to perform the switching of Y heads 64 and thetransfer of the measurement values smoothly, a distance between adjacentY heads 64 that are equipped in head units 62A and 62C is set narrowerthan a width of Y scales 39Y₁ and 39Y₂ in the X-axis direction, as isdescribed previously.

Further, in the embodiment, since a distance between adjacent X heads 66that are equipped in head units 62B and 62D is set narrower than a widthof X scales 39X₁ and 39X₂ in the Y-axis direction as is describedpreviously, when wafer stage WST is driven in the Y-axis direction asindicated by an outline arrow in FIG. 9B, X head 66 that measures theposition in the X-axis direction of wafer stage WST is sequentiallyswitched to adjacent X head 66 (e.g. X head 66 circled by a solid lineis switched to X head 66 circled by a dotted line), and the measurementvalues are transferred before and after the switching.

Next, the configuration of encoders 70A to 70F will be described,focusing on Y encoder 70A that is enlargedly shown in FIG. 10A, as arepresentative. FIG. 10A shows one Y head 64 of head unit 62A thatirradiates a detection light (measurement beam) to Y scale 39Y₁.

Y head 64 is mainly composed of three sections, which are an irradiationsystem 64 a, an optical system 64 b and a photodetection system 64 c.

Irradiation system 64 a includes a light source that emits a laser beamLB in a direction inclined at an angel of 45 degrees with respect to theY-axis and Z-axis, for example, a semiconductor laser LD, and a lens L1that is placed on the optical path of laser beam LB emitted fromsemiconductor laser LD.

Optical system 64 b is equipped with a polarization beam splitter PBSwhose separation plane is parallel to an XZ plane, a pair of reflectionmirrors R1 a and R1 b, lenses L2 a and L2 b, quarter wavelength plates(hereinafter, referred to as a λ/4 plate) WP1 a and WP1 b, refectionmirrors R2 a and R2 b, and the like.

Photodetection system 64 c includes a polarizer (analyzer), aphotodetector, and the like.

In Y encoder 70A, laser beam LB emitted from semiconductor laser LD isincident on polarization beam splitter PBS via lens L1, and is split bypolarization into two beams LB₁ and LB₂. Beam LB₁ having beentransmitted through polarization beam splitter PBS reaches reflectivediffraction grating RG that is formed on Y scale 39Y₁, via reflectionmirror R1 a, and beam LB₂ reflected off polarization beam splitter PBSreaches reflective diffraction grating RG via reflection mirror R1 b.Incidentally, “split by polarization” in this case means the splittingof an incident beam into a P-polarization component and anS-polarization component.

Predetermined-order diffraction beams that are generated fromdiffraction grating RG due to irradiation of beams LB₁ and LB₂, forexample, the first-order diffraction beams are severally converted intoa circular polarized light by λ/4 plates WP1 b and WP1 a via lenses L2 band L2 a, and reflected by reflection mirrors R2 b and R2 a and then thebeams pass through λ/4 plates WP1 b and WP1 a again and reachpolarization beam splitter PBS by tracing the same optical path in thereversed direction.

Each of the polarization directions of the two beams that have reachedpolarization beam splitter PBS is rotated at an angle of 90 degrees withrespect to the original direction. Therefore, the first-orderdiffraction beam of beam LB₁ that was previously transmitted throughpolarization beam splitter PBS is reflected off polarization beamsplitter PBS and is incident on photodetection system 64 c, and also thefirst-order diffraction beam of beam LB₂ that was previously reflectedoff polarization beam splitter PBS is transmitted through polarizationbeam splitter PBS and is synthesized concentrically with the first-orderdiffraction beam of beam LB₁ and is incident on photodetection system 64c.

Then, the polarization directions of the two first-order diffractionbeams described above are uniformly arranged by the analyzer insidephotodetection system 64 c and the beams interfere with each other to bean interference light, and the interference light is detected by thephotodetector and is converted into an electric signal in accordancewith the intensity of the interference light.

As is obvious from the above description, in Y encoder 70A, since theoptical path lengths of two beams to be interfered are extremely shortand also are almost equal to each other, the influence by airfluctuations can mostly be ignored. Then, when Y scale 39Y₁ (i.e. waferstage WST) moves in the measurement direction (the Y-axis direction, inthis case), the phase of each of the two beams changes and thus theintensity of the interference light changes. This change in theintensity of the interference light is detected by photodetection system64 c, and position information in accordance with the intensity changeis output as the measurement value of Y encoder 70A. Other encoders 70B,70C, 70D and the like are also configured similar to encoder 70A. Aseach encoder, an encoder having a resolution of, for example, around 0.1nm is used. Incidentally, in the encoders of the embodiment, as is shownin FIG. 10B, laser beam LB having a sectional shape that is elongated inthe periodic direction of grating RG may also be used, as a detectionlight. In FIG. 10B, beam LB is enlargedly shown exaggeratedly comparedwith grating RG.

In the meantime, the scales of the encoder lack the long-term mechanicalstability, because the diffraction grating is deformed due to thermalexpansion or other reasons, the pitch of the diffraction gratingpartially or entirely changes, or the like along with lapse of operatingtime. Therefore, since the errors included in the measurement valuesbecome larger along with lapse of operating time, the errors need to becorrected. In the following description, grating pitch correction andgrating deformation correction of scales that are performed in exposureapparatus 100 of the embodiment will be described referring to FIG. 11.

In FIG. 11, reference codes IBY1 and IBY2 indicate measurement beams oftwo optical axes out of multiple axes that are irradiated to refectionsurface 17 a of wafer table WTB from Y-axis interferometer 16, andreference codes IBX1 and IBX2 indicate measurement beams of two opticalaxes out of multiple axes that are irradiated to refection surface 17 bof wafer table WTB from X-axis interferometer 126. In this case,measurement beams IBY1 and IBY2 are placed symmetrically with respect tostraight line LV (which coincides with a straight line connecting thecenters of a plurality of X heads 66), and the substantial measurementaxes of Y-axis interferometer 16 coincide with straight line LV.Therefore, Y-axis interferometer 16 can measure the Y-position of wafertable WTB without Abbe errors. Similarly, measurement beams IBX1 andIBX2 are placed symmetrically with respect to straight line LH (whichcoincides with a straight line connecting the centers of a plurality ofY heads 64) that passes through the optical axis of projection opticalsystem PL and is parallel to the X-axis, and the substantial measurementaxes of X-axis interferometer 126 coincide with straight line LHparallel to the X-axis that passes through the optical axis ofprojection optical system PL. Therefore, X-axis interferometer 126 canmeasure the X-position of wafer table WTB without Abbe errors.

First, deformation of grating lines (warp of grating lines) of the Xscales and correction of pitch of grating lines of the Y scales will bedescribed. Herein, reflection surface 17 b is assumed to be an idealplane, for the sake of simplification of the description.

First of all, main controller 20 drives wafer stage WST based on themeasurement values of Y-axis interferometer 16 and X-axis interferometer126, and as is shown in FIG. 11, the position of wafer stage WST is setat a position with which Y scales 39Y₁ and 39Y₂ are placed just belowcorresponding head units 62A and 62C (at least one head) respectively,and also one ends on the +Y side of Y scales 39Y₁ and 39Y₂ (diffractiongratings) coincide with corresponding head units 62A and 62Crespectively.

Next, main controller 20 moves wafer stage WST in the +Y direction as isindicated by an arrow F in FIG. 11 at a low speed at a level in whichshort-term fluctuation of the measurement value of Y-axis interferometer16 can be ignored and with the measurement value of X-axisinterferometer 126 being fixed to a predetermined value, whilemaintaining all of the pitching amount, the rolling amount and theyawing amount to zero based on the measurement values of Y-axisinterferometer 16 and Z sensors 74 _(1,4), 74 _(2,4), 76 _(1,3) and 76_(2,3), until, for example, the other ends (the ends on the −Y side) ofY scales 39Y₁ and 39Y₂ coincide with corresponding head units 62A and62C respectively (in the effective stroke range described above). Duringthe movement, main controller 20 loads the measurement values of Ylinear encoders 70A and 70C and the measurement values of Y-axisinterferometer 16 (the measurement values by measurement beams IBY1 andIBY2) at predetermined sampling intervals, and obtains a relationbetween the measurement values of Y linear encoders 70A and 70C and themeasurement values of Y-axis interferometer 16 based on the loadedmeasurement values. That is, main controller 20 obtains a grating pitch(a distance between adjacent grating lines) of Y scales 39Y₁ and 39Y₂that are sequentially placed facing head units 62A and 62C according tothe movement of wafer stage WST and correction information on thegrating pitch. The correction information can be obtained, for example,as a correction map that shows a relation between both measurementvalues in a curved line in the case a horizontal axis indicates themeasurement value of the interferometer and a vertical axis indicatesthe measurement values of the encoders, or the like. The measurementvalues of Y-axis interferometer 16 in this case are obtained whenscanning wafer stage WST at the extremely low speed described above, andtherefore, it can be thought that the measurement values are accuratevalues in which error can be ignored, because not only a long-termfluctuation error but also a short-term fluctuation error caused by airfluctuations or the like are hardly included in the measurement values.Incidentally, a grating pitch (a distance between adjacent gratinglines) of Y scales 39Y₁ and 39Y₂ and correction information on thegrating pitch may also be obtained in the procedures similar to theabove, by moving wafer stage WST in the −Y direction within the rangedescribed above as is indicated by an arrow F′ in FIG. 11. Herein, waferstage WST is to be driven in the Y-axis direction across the range whereboth ends of Y scales 39Y₁ and 39Y₂ traverse corresponding head units62A and 62C. However, the drive range is not limited to this, and waferstage WST may also be driven, for example, in the range in the Y-axisdirection in which wafer stage WST is moved at the time of exposureoperation of a wafer.

Further, main controller 20 also obtains correction information ondeformation (warp) of grating lines 37 that have sequentially faced aplurality of X heads 66 by performing a predetermined statisticalcomputation, using the measurement values obtained from the plurality ofX heads 66 of head units 62B and 62D that are sequentially placed facingX scales 39X₁ and 39X₂ according to the movement of wafer stage WSTduring the movement and the measurement value of interferometer 16corresponding to each of the measurement values. On the computation,main controller 20 computes, for example, the measurement values (orarithmetic weighted mean) of the plurality of heads of head units 62Band 62D that are sequentially placed facing X scales 39X₁ and 39X₂ andthe like, as the correction information on grating warp. This is becausethe same variation pattern should repeatedly appear in the process wherewafer stage WST is moved in the +Y direction or the −Y direction in thecase reflection surface 17 b is an ideal plane, and therefore,correction information on deformation (warp) of grating lines 37 thathave sequentially faced the plurality of X heads 66 can be accuratelyobtained by averaging the measurement data obtained by the plurality ofX heads 66, or the like.

Incidentally, in the case reflection surface 17 b is not an ideal plane,the unevenness (bending) of the reflection surface is measured andcorrection data of the bending is obtained in advance. Then, on themovement of wafer stage WST in the +Y direction or the −Y directiondescribed above, wafer stage WST may accurately be moved in the Y-axisdirection by controlling the X-position of wafer stage WST based on thecorrection data instead of fixing the measurement value of X-axisinterferometer 126 to a predetermined value. Thus, correctioninformation on grating pitch of the Y-scales and correction informationon deformation (warp) of grating lines 37 can be obtained in the samemanner as described above. Incidentally, measurement data obtained by aplurality of X heads 66 is data in plural on the basis of differentareas on reflection surface 17 b, and the heads each measure deformation(warp) of the same grating line, and therefore, there is an incidentaleffect that the residual error after warp correction of the reflectionsurface is averaged to be approximate to the true value by the averagingdescribed above and the like (in other words, the influence of the warpresidual error can be reduced by averaging the measurement data (warpinformation on grating lines) obtained by the plurality of heads).

Next, deformation of grating lines (warp of grating lines) of the Yscales and correction of pitch of grating lines of the X scales will bedescribed. Herein, reflection surface 17 a is assumed to be an idealplane, for the sake of simplification of the description. In this case,the processing that needs to be performed is the correction describedabove with the X-axis direction and Y-axis direction interchanged.

That is, first of all, main controller 20 drives wafer stage WST, andsets the position of wafer stage WST at a position with which X scales39X₁ and 39X₂ are placed just below corresponding head units 62B and 62D(at least one head) respectively, and also one ends on the +X side (or−X side) of X scales 39X₁ and 39X₂ (diffraction gratings) coincide withcorresponding head unit 62B and 62D respectively. Next, main controller20 moves wafer stage WST in the +X direction (or −X direction) at a lowspeed at a level in which short-term fluctuation of the measurementvalue of X-axis interferometer 126 can be ignored and with themeasurement value of Y-axis interferometer 16 being fixed to apredetermined value, while maintaining all of the pitching amount, therolling amount and the yawing amount to zero based on the measurementvalues of X-axis interferometer 126 and the like, until, for example,the other ends (the ends on the −X side (or +X side)) of X scales 39X₁and 39X₂ coincide with corresponding head unit 62B and 62D respectively(in the effective stroke range described above). During the movement,main controller 20 loads the measurement values of X linear encoders 70Band 70D and the measurement values of X-axis interferometer 126 (themeasurement values by measurement beams IBX1 and IBX2) at predeterminedsampling intervals and may obtain a relation between the measurementvalues of X linear encoders 70B and 70D and the measurement values ofX-axis interferometer 126 based on the loaded measurement values. Thatis, main controller 20 obtains a grating pitch of X scales 39X₁ and 39X₂that are sequentially placed facing head units 62B and 62D according tothe movement of wafer stage WST and correction information on thegrating pitch. The correction information can be obtained, for example,as a map that shows a relation between both measurement values in acurved line in the case a horizontal axis indicates the measurementvalue of the interferometer and a vertical axis indicates themeasurement values of the encoders, or the like. The measurement valuesof X-axis interferometer 126 in this case are obtained when scanningwafer stage WST at the extremely low speed described above, andtherefore, it can be thought that the measurement values are accuratevalues in which error can be ignored, because not only a long-termfluctuation error but also a short-term fluctuation error caused by airfluctuations are hardly included in the measurement values.

Further, main controller 20 also obtains correction information ondeformation (warp) of grating lines 38 that have sequentially faced aplurality of Y heads 64 by performing a predetermined statisticalcomputation, using the measurement values obtained from the plurality ofY heads 64 of head units 62A and 62C that are sequentially placed facingY scales 39Y₁ and 39Y₂ according to the movement of wafer stage WSTduring the movement and the measurement value of interferometer 126corresponding to each of the measurement values. On the computation,main controller 20 computes, for example, the measurement values (orarithmetic weighted mean) of the plurality of heads of head units 62Aand 62C that are sequentially placed facing Y scales 39Y₁ and 39Y₂ andthe like, as the correction information on grating warp. This is becausethe same variation pattern should repeatedly appear in the process wherewafer stage WST is moved in the +X direction or the −X direction in thecase reflection surface 17 a is an ideal plane, and therefore,correction information on deformation (warp) of grating lines 38 thathave sequentially faced the plurality of Y heads 64 can be accuratelyobtained by averaging the measurement data obtained by the plurality ofY heads 64, or the like.

Incidentally, in the case where reflection surface 17 a is not an idealplane, the unevenness (bending) of the reflection surface is measuredand correction data of the bending is obtained in advance. Then, on themovement of wafer stage WST in the +X direction or the −X directiondescribed above, wafer stage WST may accurately be moved in the X-axisdirection by controlling the Y-position of wafer stage WST based on thecorrection data instead of fixing the measurement value of Y-axisinterferometer 16 to a predetermined value. Thus, correction informationon grating pitch of the X-scales and correction information ondeformation (warp) of grating lines 38 can be obtained in the samemanner as described above.

As is described above, main controller 20 obtains correction informationon grating pitch of the Y scales and correction information ondeformation (warp) of grating lines 37, and correction information ongrating pitch of the X scales and correction information on deformation(warp) of grating lines 38 at each predetermined timing, for example,with respect to each lot, or the like.

Then, during the exposure processing of wafers in a lot or the like,while correcting the measurement values obtained from head units 62A and62C (i.e. the measurement values of encoders 70A and 70C) based on thecorrection information on grating pitch of the Y scales and thecorrection information on deformation (warp) of grating lines 38, maincontroller 20 performs position control of wafer stage WST in the Y-axisdirection. Thus, it becomes possible to perform position control ofwafer stage WST in the Y-axis direction with good accuracy using Ylinear encoders 70A and 70C without being affected by change over timein grating pitch of the Y scales and warp of grating lines 38.

Further, during the exposure processing of wafers in a lot or the like,while correcting the measurement values obtained from head units 62B and62D (i.e. the measurement values of encoders 70B and 70D) based on thecorrection information on grating pitch of the X scales and thecorrection information on deformation (warp) of grating lines 37, maincontroller 20 performs position control of wafer stage WST in the X-axisdirection. Thus, it becomes possible to perform position control ofwafer stage WST in the X-axis direction with good accuracy using Xlinear encoders 70B and 70D without being affected by change over timein grating pitch of the X scales and warp of grating lines 37.

Incidentally, in the description above, correction information ongrating pitch and grating line warp is to be obtained for all of Yscales 39Y₁ and 39Y₂ and X scales 39X₁ and 39X₂. However, the presentinvention is not limited to this, and correction information on gratingpitch and grating line warp may be obtained for either one of Y scales39Y₁ and 39Y₂ or X scales 39X₁ and 39X₂, or the correction informationon either one of grating pitch or grating line warp may be obtained forboth of Y scales 39Y₁ and 39Y₂ and X scales 39X₁ and 39X₂. For example,in the case only correction information on grating line warp isobtained, wafer stage WST may be moved in the Y-axis direction based onthe measurement values of Y linear encoders 70A and 70C without usingY-axis interferometer 16, or wafer stage WST may be moved in the X-axisdirection based on the measurement values of X linear encoders 70B and70D without using X-axis interferometer 126.

Next, wafer alignment performed in exposure apparatus 100 of theembodiment will be briefly described using FIGS. 12A to 12C.Incidentally, the details will be described later.

Herein, the operation in the case where 16 of colored shot areas AS, onwafer W on which a plurality of shot areas are formed in the layout(shot map) shown in FIG. 12C, are to serve as alignment shot areas willbe described. Incidentally, measurement stage MST is omitted in FIGS.12A and 12B.

It is assumed that position adjustment in the X-axis direction ofsecondary alignment systems AL2 ₁ to AL2 ₄ has been performed beforehandin accordance with the placement of alignment shot areas AS.Incidentally, a specific method of the position adjustment of secondaryalignment systems AL2 ₁ to AL2 ₄ will be described later.

First, main controller 20 moves wafer stages WST, on which the positionof the wafer W center is set at loading position LP, toward an obliquelyupper left direction in FIG. 12A, and sets the position of wafer stageWST at a predetermined position (alignment starting position to bedescribed later) at which the center of wafer W is located on straightline LV. The movement of wafer stage WST in this case is performed bymain controller 20 driving each motor of stage drive system 124 based onthe measurement value of X encoder 70D and the measurement value ofY-axis interferometer 16. In a state where the position of wafer stageWST is set at the alignment starting position, control of the position(including the θz rotation) within the XY plane of wafer table WTB onwhich wafer W is mounted is performed based on the measurement values oftwo X heads 66 that are equipped in head unit 62D and face X scales 39X₁and 39X₂ respectively, and Y heads 64Y₂ and 64Y₁ that face Y scale 39Y₁ad 39Y₂ respectively (four encoders).

Next, main controller 20 moves wafer stage WST in the +Y direction by apredetermined distance based on the measurement values of the fourencoders, and sets the position of wafer stage WST at the position shownin FIG. 12A. And, main controller 20 almost simultaneously andindividually detects alignment marks (refer to star-shaped marks in FIG.12A) arranged in the three first alignment shots areas AS using primaryalignment system AL1 and secondary alignment systems AL2 ₂ and AL2 ₃,and links the detection results of the above three alignment systemsAL1, AL2 ₂ and AL2 ₃ and the measurement values of the four encodersdescribed above at the time of the detection and stores them in a memory(not shown). Incidentally, secondary alignment systems AL2 ₁ and AL2 ₄on both sides that do not detect the alignment marks at this point intime may be made not to irradiate a detection light to wafer table WTB(or a wafer), or may be made to irradiate a detection light. Further, inthe wafer alignment in the embodiment, the position of wafer stage WSTin the X-axis direction is set so that primary alignment system AL1 isplaced on the centerline of wafer table WTB, and primary alignmentsystem AL1 detects the alignment mark in the alignment shot area that islocated on a meridian of the wafer. Incidentally, the alignment mark mayalso be formed inside each shot area on wafer W, but in the embodimentthe alignment mark is to be formed outside each shot area, that is, on astreet line (scribe line) that divides multiple shot areas on wafer W.

Next, main controller 20 moves wafer stage WST in the +Y direction by apredetermined distance based on the measurement values of the fourencoders, and sets the position of wafer stage WST at a position atwhich five alignment systems AL1 and AL2 ₁ to AL2 ₄ can almostsimultaneously and individually detect the alignment marks arranged inthe five second alignment shot areas AS on wafer W, and almostsimultaneously and individually detects the five alignment marks usingfive alignment systems AL1 and AL2 ₁ to AL2 ₄, and then links thedetection results of five alignment systems AL1 and AL2 ₁ to AL2 ₄ andthe measurement values of the four encoders at the time of the detectionand stores them in a memory (not shown).

Next, main controller 20 moves wafer stage WST in the +Y direction by apredetermined distance based on the measurement values of the fourencoders, and sets the position of wafer stage WST at a position atwhich five alignment systems AL1 and AL2 ₁ to AL2 ₄ can almostsimultaneously and individually detect the alignment marks arranged inthe five third alignment shot areas AS on wafer W, and almostsimultaneously and individually detects the five alignment marks (referto star-shaped marks in FIG. 12B) using five alignment systems AL1 andAL2 ₁ to AL2 ₄, and then links the detection results of five alignmentsystems AL1 and AL2 ₁ to AL2 ₄ and the measurement values of the fourencoders at the time of the detection and stores them in a memory (notshown).

Next, main controller 20 moves wafer stage WST in the +Y direction by apredetermined distance based on the measurement values of the fourencoders, and sets the position of wafer stage WST at a position atwhich the alignment marks arranged in the three fourth alignment shotareas AS on wafer W can be almost simultaneously and individuallydetected using primary alignment system AL1 and secondary alignmentsystems AL2 ₂ and AL2 ₃, and almost simultaneously and individuallydetects the three alignment marks using three alignment systems AL1, AL2₂ and AL2 ₃, and then links the detection results of three alignmentsystems AL1, AL2 ₂ and AL2 ₃ and the measurement values of the fourencoders at the time of the detection and stores them in a memory (notshown).

Then, main controller 20 computes an array of all the shot areas onwafer W on a coordinate system (e.g. an XY coordinate system using theoptical axis of projection optical system PL as its origin) that is setby the measurement axes of the four encoders (four head units), byperforming a statistical computation by the EGA method, which isdisclosed in, for example, Kokai (Japanese Unexamined Patent ApplicationPublication) No. 61-044429 (the corresponding U.S. Pat. No. 4,780,617)and the like, using the detection results of a total of 16 alignmentmarks and the corresponding measurement values of the four encodersobtained in the manner described above, and the baseline of secondaryalignment system AL2 _(n).

As is described above, in the embodiment, by moving wafer stage WST inthe +Y direction and setting the position of wafer stage WST at fourpoints on the moving route, position information of alignment marks inthe alignment shot areas AS at 16 points in total can be obtained in aremarkably shorter period of time, compared with the case where a singlealignment system sequentially detects alignment marks at 16 points. Inthis case, for example, as it is easier to understand in particular whenconsidering alignment systems AL1, AL2 ₂ and AL2 ₃, each of alignmentsystems AL1, AL2 ₂ and AL2 ₃ detects a plurality of alignment marksarrayed along the Y-axis direction that are sequentially placed withinthe detection area (e.g. corresponding to the irradiation area of thedetection light), associated with the operation of moving wafer stageWST described above. Therefore, on the foregoing measurement of thealignment marks, it is not necessary to move wafer stage WST in theX-axis direction.

Further, in this case, the number of detection points (the number ofmeasurement points) of alignment marks on wafer W that are almostsimultaneously detected by a plurality of alignment systems differsdepending on the position within the XY plane of wafer stage WST (theY-position in particular (i.e. the access degree of wafer W to aplurality of alignment systems). Therefore, when moving wafer stage WSTin the Y-axis direction that is orthogonal to the array direction(X-axis direction) of a plurality of alignment systems, the marks atpositions different from one another on wafer W can be detectedsimultaneously using the required number of alignment systems, inaccordance with the position of wafer stage WST, in other words, inaccordance with the shot array on wafer W.

Meanwhile, the surface of wafer W is not an ideal plane and normally hassome unevenness. Accordingly, in the case the simultaneous measurementby a plurality of alignment systems described above is performed only ata certain position in the Z-axis direction (direction parallel tooptical axis AX of projection optical system PL) of wafer table WTB, itis highly probable that at least one alignment system performs detectionof an alignment mark in a defocused state. Thus, in the embodiment,measurement error of positions of alignment marks, which is caused bydetection of alignment marks performed in a defocused state, issuppressed in the manner described below.

That is, main controller 20 controls stage drive system 124 (Z-levelingmechanism (not shown)) and a plurality of alignment systems AL1 and AL2₁ to AL2 ₄ so that each of alignment marks formed at the positions thatare different from one another on wafer W is almost simultaneouslydetected by each alignment system corresponding to each alignment mark,while changing a relative positional relation in the Z-axis direction(focus direction) perpendicular to the XY plane between alignmentsystems AL1 and AL2 ₁ to AL2 ₄ and wafer W mounted on wafer table WTB(wafer stage WST) using the Z-leveling mechanism that constitutes partof stage drive system 124, at each position at which the position ofwafer stage WST is set for detecting the alignment marks in therespective alignment shot areas described above.

FIGS. 13A to 13C show a status where detection of marks on wafer W isperformed by five alignment systems AL1 and AL2 ₁ to AL2 ₄ in the stateshown in FIG. 12B where the position of wafer stage WST is set at thedetection position of alignment marks in the third alignment shot areasdescribed above. Each of FIGS. 13A to 13C shows a status where wafertable WTB (wafer W) is located at the different Z-position and differentalignment marks are almost simultaneously being detected using alignmentsystems AL1 and AL2 ₁ to AL2 ₄. In the state of FIG. 13A, alignmentsystems AL2 ₁ and AL2 ₄ on both sides are in a focused state and theremaining alignment systems are in a defocused state. In the state ofFIG. 13B, alignment systems AL2 ₂ and AL2 ₃ are in a focused state andthe remaining alignment systems are in a defocused state. In the stateof FIG. 13C, only alignment system AM in the center is in a focusedstate and the remaining alignment systems are in a defocused state.

In this manner, by performing simultaneous measurement of alignmentmarks by alignment systems AL1 and AL2 ₁ to AL2 ₄ while changing arelative positional relation in the Z-axis direction (focus direction)between a plurality of alignment systems AL1 and AL2 ₁ to AL2 ₄ andwafer W mounted on wafer table WTB (wafer stage WST) by changing theZ-position of wafer table WTB (wafer W), any of the alignment systemscan measure the alignment marks in a substantially best focused state.Accordingly, main controller 20 can accurately detect the marks formedat positions different from one another on wafer W without beingaffected by unevenness of the wafer W surface or the best focusdifference among a plurality of alignment systems, by preferentiallyusing the detection result of the mark, for example, in the mostfavorable focused state of each alignment system, or the like.

Incidentally, in the description above, for example, the detectionresult of the mark in the most favorable focused state of each alignmentsystem is to be preferentially used. However, the present invention isnot limited to this, and main controller 20 may obtain positioninformation of alignment marks also using the detection results of themarks in a defocused state. In this case, the detection results of themarks in a defocused state may also be used by multiplying the detectionresults by the weight in accordance with the defocused state. Further,the detection result of the mark in the defocused state is sometimesbetter than that in the best focused state, for example, depending onmaterials of layers formed on the wafer. In this case, detection of themarks is performed in the focus state with which the most favorableresult can be obtained, that is, in a defocused state, and positioninformation of the marks may be obtained using the detection results.

Further, as can be seen from FIGS. 13A to 13C, all the optical axes ofall the alignment systems do not always coincide with the same idealdirection (Z-axis direction) accurately, and due to the influence ofthis tilt (telecentricity) of the optical axes with respect to theZ-axis, the detection results of positions of the alignment marks couldinclude error. Accordingly, it is preferable that the tilt with respectto the Z-axis of the optical axes of all the alignment systems ismeasured in advance, and the detection results of positions of thealignment marks are corrected based on the measurement results.

Next, baseline measurement (baseline check) of primary alignment systemAL1 will be described. Herein, the baseline of primary alignment systemAL1 means a positional relation (or a distance) between a projectionposition where a pattern (e.g. a pattern of reticle R) is projected byprojection optical system PL and a detection center of primary alignmentsystem AL1.

a. At the point in time when baseline measurement of primary alignmentsystem AL1 is started, as is shown in FIG. 14A, nozzle unit 32 formsliquid immersion area 14 between projection optical system PL and atleast one of measurement table MTB and CD bar 46. That is, wafer stageWST and measurement stage MST are in a state of separating from eachother.

On baseline measurement of primary alignment system AL1, first of all,as is shown in FIG. 14A, main controller 20 detects (observes) fiducialmark FM located in the center on measurement plate 30 with primaryalignment system AL1 (refer to a star-shaped mark in FIG. 14A). Then,main controller 20 makes the detection result of primary alignmentsystem AL1 correspond to the measurement values of encoders 70A to 70Dat the time of the detection, and stores them in a memory. Hereinafter,this processing is referred to as a Pri-BCHK former processing, for thesake of convenience. On the Pri-BCHK former processing, the positionwithin the XY plane of wafer table WTB is controlled based on two Xheads 66 indicated by being circled in FIG. 14A that face X scales 39X₁and 39X₂ (encoders 70B and 70D), and two Y heads 64Y₂ and 64Y₁ indicatedby being circled in FIG. 14A that face Y scales 39Y₁ and 39Y₂ (encoders70A and 70C).

b. Next, as is shown in FIG. 14B, main controller 20 starts movement ofwafer stage WST in the +Y direction so that measurement plate 30 islocated directly below projection optical system PL. After starting themovement in the +Y direction of wafer stage WST, main controller 20detects the approaching of wafer stage WST and measurement stage MSTbased on the outputs of clearance detection sensors 43A and 43C. Beforeand after that, that is, during the movement in the +Y direction ofwafer stage WST, main controller 20 starts to open shutters 49A and 49Bvia drive mechanisms 34A and 34B, and permits the further approaching ofwafer stage WST and measurement stage MST by opening the shutters.Further, main controller 20 confirms the opening of shutters 49A and 49Bbased on detection results of opening/closing sensor 101.

c. Next, immediately after detecting that wafer stage WST andmeasurement stage MST come into contact with each other (or come closertogether at a distance of around 300 μm) based on the outputs ofcollision detection sensors 43B and 43D, main controller 20 stops waferstage WST. After that, main controller 20 further moves measurementstage MST and wafer stage WST integrally in the +Y direction whilekeeping a contact state of measurement stage MST and wafer stage WST(or, keeping a distance of around 300 μm). Then, in the middle of themovement, liquid immersion area 14 is delivered from CD bar 46 to wafertable WTB.

d. Then, when wafer stage WST reaches the position shown in FIG. 14B,main controller 20 stops both stages WST and MST, and measures projectedimages (aerial images) of a pair of measurement marks on reticle R thatare projected by projection optical system PL, using aerial imagemeasuring unit 45 including measurement plate 30. The aerial images ofmeasurement marks in pairs are severally measured in the aerial imagemeasurement operation by a slit-scan method using a pair of aerial imagemeasurement slit patterns SL, similar to the method that is disclosedin, for example, Kokai (Japanese Unexamined Patent ApplicationPublication) No. 2002-014005 (the corresponding U.S. Patent ApplicationPublication No. 2002/0041377) referred to previously and the like, andthen stores the measurement results (aerial image intensity inaccordance with the XY position of wafer table WTB) in a memory.Hereinafter, this measurement processing of aerial images of measurementmarks in pairs on reticle R is referred to as a Pri-BCHK latterprocessing for the sake of convenience. On the Pri-BCHK latterprocessing, the position within the XY plane of wafer table WTB iscontrolled based on two X heads 66 indicated by being circled in FIG.14B that face X scales 39X₁ and 39X₂ (encoders 70B and 70D), and two Yheads 64 indicated by being circled in FIG. 14B that face Y scales 39Y₁and 39Y₂ (encoders 70A and 70C).

Then, main controller 20 computes the baseline of primary alignmentsystem AL1 based on the results of the Pri-BCHK former processing andthe results of the Pri-BCHK latter processing described above.

Incidentally, at the point in time when the baseline measurement ofprimary alignment system AL1 ends (i.e. the Pri-BCHK latter processingends) as is described above, measurement stage MST and wafer stage WSTare in a contact state (or a state of being separate from each other ata distance of around 300 μm).

Next, a baseline measurement operation of secondary alignment system AL2_(n) (n=1 to 4), which is performed mainly (to a wafer at the head of alot) right before the processing to wafers in the lot is started, willbe described. Herein, the baseline of secondary alignment system AL2_(n) means a relative position of (a detection center of) each secondaryalignment system. AL2 _(n) with (the detection center of) primaryalignment system AL1 as a datum. Incidentally, the position in theX-axis direction of secondary alignment system AL2 _(n) (n=1 to 4) isassumed to be set by being driven by rotation drive mechanism 60 _(n),for example, in accordance with the shot map data of the wafers in thelot.

e. On the baseline measurement of the secondary alignment systemperformed to the wafer at the head of a lot (hereinafter, also referredto as “Sec-BCHK” as needed), first of all, as is shown in FIG. 15A, maincontroller 20 detects a specific alignment mark on wafer W (processwafer) at the head of a lot with primary alignment system AL1 (refer toa star-shaped mark in FIG. 15A). Then, main controller 20 makes thedetection result correspond to the measurement values of encoders 70A to70D at the time of the detection, and stores them in a memory. In thestate of FIG. 15A, the position within the XY plane of wafer table WTBis controlled by main controller 20 based on two X heads 66 facing Xscales 39X₁ and 39X₂ (encoders 70B and 70D) and two Y heads 64Y₂ and64Y₁ facing Y scales 39Y₁ and 39Y₂ (encoders 70A and 70C).

f. Next, main controller 20 moves wafer stage WST in the −X direction bya predetermined distance, and as is shown in FIG. 15B, detects thespecific alignment mark with secondary alignment system AL2 ₁ (refer toa star-shaped mark in FIG. 15B), and makes the detection resultcorrespond to the measurement values of encoders 70A to 70D and storesthem in a memory. In the state of FIG. 15B, the position within the XYplane of wafer table WTB is controlled based on two X heads 66 facing Xscales 39X₁ and 39X₂ (encoders 70B and 70D) and two Y heads 64 facing Yscales 39Y₁ and 39Y₂ (encoders 70A and 70C).

g. Similarly, main controller 20 sequentially moves wafer stage WST inthe +X direction and sequentially detects the specific alignment markwith the remaining secondary alignment systems AL2 ₂, AL2 ₃ and AL2 ₄,and then sequentially makes the detection results correspond to themeasurement values of encoders 70A to 70D at the time of the detectionand stores them in a memory.

h. Then, main controller 20 computes the baseline of each secondaryalignment system AL2 _(n) based on the processing results of the above“e”, and the processing results of the above “f” or “g”.

In this manner, since the baseline of each secondary alignment systemAL2 _(n) is obtained by detecting the same alignment mark on wafer Wwith primary alignment system AL1 and each secondary alignment systemAL2 _(n) using wafer W (process wafer) at the head of a lot, thedifference in detection offset among the alignment systems caused by theprocess can be corrected by this processing consequently. Incidentally,baseline measurement of secondary alignment system AL2 _(n) may also beperformed using a datum mark on wafer stage WST or measurement stageMST, instead of the alignment mark on the wafer. In this case, fiducialmark FM of measurement plate 30 used in the baseline measurement ofprimary alignment system AL1 may be used, that is, fiducial mark FM mayalso be measured by each secondary alignment system AL2 _(n). Or, forexample, the “n” number of datum marks are arranged on wafer stage WSTor measurement stage MST in the same positional relation as that ofsecondary alignment system AL2 _(n), and detection of the datum marks bysecondary alignment system AL2 _(n) may also be executable almostsimultaneously. As the datum marks, for example, reference marks M of CDbar 46 may also be used. Moreover, the datum marks for baselinemeasurement of secondary alignment system AL2 _(n) may be arranged onwafer stage WST in a predetermined positional relation with fiducialmark FM for baseline measurement of primary alignment system AL1, anddetection of the datum marks by secondary alignment system AL2 _(n) mayalso be executable almost simultaneously with detection of fiducial markFM by primary alignment system AL1. In this case, the number of datummarks for baseline measurement of secondary alignment system AL2 _(n)may be one, or the datum marks may be arranged in plural, for example,the same number as the number of secondary alignment system AL2 _(n).Further, in the embodiment, since each of primary alignment system AL1and secondary alignment system AL2 _(n) can detect two-dimensional marks(X and Y marks), the baselines in the X-axis and the Y-axis directionsof secondary alignment system AL2 _(n) can be obtained simultaneously byusing the two-dimensional marks at the time of baseline measurement ofsecondary alignment system AL2 _(n). In the embodiment, fiducial mark FMand reference marks M, and the alignment marks on the wafer include, forexample, the one-dimensional X mark and Y mark in which a plurality ofline marks are periodically arrayed in the X-axis and Y-axis directionsrespectively.

Next, a Sec-BCHK operation, which is performed at predetermined timingduring the processing of wafers in a lot, for example, a period fromwhen exposure of a wafer ends until when the loading of the next waferon wafer table WTB is completed, that is, during wafer replacement, willbe described. In this case, because the Sec-BCHK is performed atintervals of each wafer replacement, hereinafter the Sec-BCHK is alsoreferred to as the Sec-BCHK (interval).

On this Sec-BCHK (interval), as is shown in FIG. 16, main controller 20moves measurement stage MST so that straight line LV on which thedetection center of primary alignment system AL1 is placed substantiallycoincides with centerline CL and also CD bar 46 faces primary alignmentsystem AL1 and secondary alignment system AL2 _(n). Then, maincontroller 20 adjusts the θz rotation of CD bar 46 based on themeasurement values of a pair of reference gratings 52 on CD bar 46 and Yheads 64Y₁ and 64Y₂ indicated by being circled in FIG. 16 that face thepair of reference gratings 52 respectively (Y-axis linear encoders 70Eand 70F), and also adjusts the XY-position of CD bar 46, for example,using the measurement values of the interferometers, based on themeasurement values of primary alignment system AL1 indicated by beingcircled in FIG. 16 that detects reference mark M located on centerlineCL of measurement table MTB or in the vicinity thereof.

Then, in this state, main controller 20 obtains each of the baselines offour secondary alignment systems AL2 ₁ to AL2 ₄, by simultaneouslymeasuring reference mark M on CD bar 46 that is located within the fieldof each of the secondary alignment systems using four secondaryalignment systems AL2 ₁ to AL2 ₄. Then, on the subsequent processing,drift of the baselines of four secondary alignment systems AL2 ₁ to AL2₄ is corrected by using the newly measured baselines.

Incidentally, the Sec-BCHK (interval) described above is to be performedby simultaneous measurement of different reference marks by a pluralityof secondary alignment systems. However, the present invention is notlimited to this, and each of the baselines of four secondary alignmentsystems AL2 ₁ to AL2 ₄ may also be obtained by sequentially(nonsimultaneously) measuring the same reference mark M on CD bar 46with a plurality of secondary alignment systems.

Next, the operation of position adjustment of secondary alignment systemAL2 _(n) will be briefly described based on FIGS. 17A and 17B.

It is assumed that a positional relation between primary alignmentsystem AL1 and four secondary alignment systems AL2 ₁ to AL2 ₄ is thepositional relation shown in FIG. 17A, before the adjustment.

As is shown in FIG. 17B, main controller 20 moves measurement stage MSTso that primary alignment system AL1 and four secondary alignmentsystems AL2 ₁ to AL2 ₄ are located above CD bar 46. Next, in the similarmanner to the case of the Sec-BCHK (interval) described above, maincontroller 20 adjusts the θz rotation of CD bar 46 based on themeasurement values of Y-axis linear encoders 70E and 70F (Y heads 64 y ₁and 64 y ₂), and also adjust the XY-position of CD bar 46 based on themeasurement values of primary alignment system AL1 that detectsreference mark M located on centerline CL of measurement table MTB or inthe vicinity thereof. Simultaneously with this adjustment, maincontroller 20 rotates each of arms 56 at the tip of which each secondaryalignment system AL2 _(n) is arranged, around each rotation center asindicated by arrows in FIG. 17B, by driving rotation drive mechanisms 60₁ to 60 ₄ based on shot map information including information on sizeand placement of alignment shot areas on a wafer to be exposed next(i.e. placement of alignment marks on the wafer). In this case, maincontroller 20 stops the rotation of each arm 56 at the position where adesired reference mark M on CD bar 46 is located in the field (detectionarea) of each secondary alignment system AL2 _(n), while monitoringdetection results of each secondary alignment system AL2 _(n). Thus, thebaseline of secondary alignment system AL2 _(n) is adjusted (changed) inaccordance with the placement of alignment marks arranged in thealignment shot areas to be detected. In other words, the position in theX-axis direction of the detection area of secondary alignment system AL2_(n) is changed. Thus, only by moving wafer W in the Y-axis direction, aplurality alignment marks whose positions in the X-axis direction aresubstantially the same and whose positions in the Y-axis direction aredifferent on wafer W can be sequentially detected by each secondaryalignment system AL2 _(n). In the embodiment, in the wafer alignmentoperation, that is, in the detection operation of the alignment marks onthe wafer by primary alignment system AL1 and secondary alignment systemAL2 _(n), wafer W is to be one-dimensionally moved only in the Y-axisdirection. However, during the operation, the detection area of at leastone secondary alignment system AL2 _(n) and wafer W may also berelatively moved in a direction different from the Y-axis direction(e.g. in the X-axis direction). In this case, the position of thedetection area may be adjusted by the movement of secondary alignmentsystem AL2 _(n), or only wafer W may be moved in view of the adjustmentperiod of time or change in the baseline.

Then, after the baseline of secondary alignment system AL2 _(n) isadjusted in this manner, main controller 20 fixes each arm 56 _(n) to amain frame (not shown) by suction by activating each vacuum pad 58 _(n).Thus, a state of each arm 56 _(n) after the rotation angle adjustment ismaintained.

Incidentally, in the above description, reference marks M formed atdifferent positions on CD bar 46 are to be simultaneously andindividually detected with five alignment systems AL1 and AL2 ₁ to AL2₄. However, the present invention is not limited to this, and thebaseline of secondary alignment system AL2 _(n) can also be adjusted,for example, by simultaneously and individually detecting alignmentmarks formed at different positions on wafer W (process wafer) with fivealignment systems AL1 and AL2 ₁ to AL2 ₄ and adjusting the rotation ofeach arm 56 _(n). Further, in the embodiment, the baseline (the positionof the detection area) of secondary alignment system AL2 _(n) is to beadjusted using reference marks M of CD bar 46 or the like. However, theadjustment operation is not limited to this, and for example, secondaryalignment system AL2 _(n) only has to be moved to a target positionwhile measuring its position with the sensor described above. In thiscase, it is only necessary to employ the sequence in which the baselinethat has been measured before the movement is corrected based on theposition or the movement amount of secondary alignment system AL2 _(n)measured by the sensor, or the baseline measurement is executed againafter the movement, or at least the baseline measurement of secondaryalignment system AL2 _(n) is performed after the movement.

Next, detection of position information (surface position information)of the wafer W surface in the Z-axis direction (hereinafter, referred toas focus mapping) that is performed in exposure apparatus 100 of theembodiment will be described.

On the focus mapping, as is shown in FIG. 18A, main controller 20controls the position within the XY plane of wafer table WTB based on Xhead 66 facing X scale 39X₂ (X linear encoder 70D) and two Y heads 64Y₂and 64Y₁ facing Y scales 39Y₁ and 39Y₂ respectively (Y linear encoders70A and 70C). In the state of FIG. 18A, a straight line (centerline)parallel to the Y-axis that passes through the center of wafer table WTB(which substantially coincides with the center of wafer W) coincideswith straight line LV.

Then, in this state, main controller 20 starts scanning of wafer stageWST in the +Y direction, and after starting the scanning, activates(turns ON) both Z sensors 72 a to 72 d and the multipoint AF system (90a, 90 b) by the time when detection beams of the multipoint AF system(90 a, 90 b) begin to be irradiated on wafer W due to movement of waferstage WST in the +Y direction.

Then, in a state where Z sensors 72 a to 72 d and the multipoint AFsystem (90 a, 90 b) simultaneously operate, as is shown in FIG. 18B,position information (surface position information) of the wafer tableWTB surface (surface of plate 28) in the Z-axis direction that ismeasured by Z sensors 72 a to 72 d and position information (surfaceposition information) of the wafer W surface in the Z-axis direction ata plurality of detection points that is detected by the multipoint AFsystem (90 a, 90 b) are loaded at predetermined sampling intervalsduring a period when wafer stage WST is proceeding in the +Y direction,and loaded three kinds of information, i.e. two kinds of the loadedsurface position information and the measurement values of Y linearencoders 70A and 70C at each sampling timing are made to correspond toone another, and are sequentially stored in a memory (not shown).

Then, when the detection beams of the multipoint AF system (90 a, 90 b)begin to miss wafer W, main controller 20 ends the sampling describedabove and converts the surface position information at each detectionpoint of the multipoint AF system (90 a, 90 b) into data, using thesurface position information by Z sensors 72 a to 72 d that has beenloaded simultaneously, as a datum.

More specifically, based on the average value of the measurement valuesof Z sensors 72 a and 72 b, surface position information at apredetermined point (e.g. corresponding to a midpoint between therespective measurement points of Z sensors 72 a and 72 b, that is, apoint on the substantially same X-axis as the array of a plurality ofdetection points of the multipoint AF system (90 a, 90 b): hereinafter,this point is referred to as a left measurement point) on an area (areawhere Y scale 39Y₂ is formed) in the vicinity of the −X side end portionof plate 28 is obtained. Further, based on the average value of themeasurement values of Z sensors 72 c and 72 d, surface positioninformation at a predetermined point (e.g. corresponding to a midpointbetween the respective measurement points of Z sensors 72 c and 72 d,that is, a point on the substantially same X-axis as the array of aplurality of detection points of the multipoint AF system (90 a, 90 b):hereinafter, this point is referred to as a right measurement point) onan area (area where Y scale 39Y₁ is formed) in the vicinity of the +Xside end portion of plate 28 is obtained. Then, as is shown in FIG. 18C,main controller 20 converts the surface position information at eachdetection point of the multipoint AF system (90 a, 90 b) into surfaceposition data z1 to zk using a straight line that connects the surfaceposition of a left measurement point P1 and the surface position of aright measurement point P2 as a datum. Main controller 20 performs suchconversion to the information loaded at all the sampling timings.

Since the foregoing converted data is obtained in advance as isdescribed above, afterward, for example, on exposure or the like, theZ-position and the tilt (mainly the θy rotation) with respect to the XYplane of wafer table WTB are computed, by measuring the wafer table WTBsurface (a point on the area where Y scale 39Y₂ is formed and a point onthe area where Y scale 39Y₁ is formed) with Z sensors 74 _(1,j) and 74_(2,j), and 76 _(1,q) and 76 _(2,q). By using the computed Z-positionand tilt with respect to the XY plane of wafer table WTB and surfaceposition data z1 to zk described above, surface position control of theupper surface of wafer W can be performed without actually obtainingsurface position information of the wafer surface. Accordingly, sincethere is no problem even if the multipoint AF system is placed at aposition away from projection optical system PL, the focus mapping ofthe embodiment can suitably be applied also to an exposure apparatuswhose working distance is short, or the like.

Incidentally, in the description above, the surface position of leftmeasurement point P1 and the surface position of right measurement pointP2 are to be computed based on the average value of measurement valuesof Z sensors 72 a and 72 b and the average value of measurement valuesof Z sensors 72 c and 72 d respectively. However, the present inventionis not limited to this, and the surface position information at eachdetection point of the multipoint AF system (90 a, 90 b) may also beconverted into surface position data, for example, using a straight linethat connects the surface positions measured by Z sensors 72 a and 72 c,as a datum. In this case, the difference between the measurement valueof Z sensor 72 a and the measurement value of Z sensor 72 b obtained ateach sampling timing, and the difference between the measurement valueof Z sensor 72 c and the measurement value of Z sensor 72 d obtained ateach sampling timing are obtained severally in advance. Then, whenperforming surface position control at the time of exposure or the like,by measuring the wafer table WTB surface with Z sensors 74 _(1,j) and 74_(2,j), and 76 _(1,q) and 76 _(2,q) and computing the Z-position and thetilt (not only the θy rotation but also the θx rotation) with respect tothe XY plane of wafer table WTB, surface position control of wafer W canbe performed using the computed Z-position and tilt with respect to theXY plane of wafer table WTB, and surface position data z1 to zkdescribed above and the differences described above, without actuallyobtaining surface position information of the wafer surface.

The description so far is made assuming that unevenness does not existon the wafer table WTB surface. In actual, however, as is shown in FIG.18C, there is unevenness on the surface of wafer table WTB, that is, thesurface of a first partial area 28 b ₁ where Y scale 39Y₂ is formed, thesurface of a second partial area 28 b ₂ where Y scale 39Y₁ is formed, orthe like. However, even in the case unevenness exits on the surface ofwafer table WTB as is described above, surface position control withextremely high precision can be performed at a point on a meridian ofwafer W (a straight line parallel to the Y-axis that passes through thewafer center).

The surface position control at a point on the meridian will bedescribed below.

When the focus mapping is performed, Z sensors 72 a to 72 d that serveas datums when performing the mapping detect surface positioninformation of certain positions (XY coordinate positions) on the wafertable WTB surface. Then, as is obvious from the description above, thefocus mapping is performed fixing the X-position of wafer stage WSTwhile moving wafer stage WST straight in the +Y direction. In otherwords, the lines (on the surface of second water repellent plate 28 b)that Z sensors 72 a to 72 d detect the surface position information whenperforming the focus mapping also become straight lines parallel to theY-axis.

When the focus mapping is being performed (when wafer stage WST ismoving in the +Y direction), the shot area located on the meridian ofthe wafer is to be placed at an exposure position (below projectionoptical system PL) without moving wafer stage WST in the X-axisdirection. When the shot area on the meridian reaches the exposureposition, a pair of Z sensors 74 _(1,4) and 74 _(2,4) that are on thesame straight line parallel to the Y-axis as Z sensors 72 a and 72 b,and a pair of Z sensors 76 _(1,3) and 76 _(2,3) that are on the samestraight line parallel to the Y-axis as Z sensors 72 c and 72 d are todetect surface position information at points that are the same as thepoints on wafer table WTB at which Z sensors 72 a and 72 b, and Zsensors 72 c and 72 d severally detect surface position information atthe time of focus mapping. That is, the datum surface measured by the Zsensors that serves as a datum in the detection of surface positioninformation by the multipoint AF system (90 a, 90 b) is the same at thetime of focus mapping and at the time of exposure. Therefore, whenexposing the shot area on the meridian, even if unevenness or undulationoccurs on the surface of wafer table WTB, focus control of the wafer onexposure can be performed using the Z-position obtained at the time offocus mapping without change, without taking the unevenness orundulation into consideration, and therefore highly accurate focuscontrol can be performed.

When exposing the shot areas other than the shot area on the meridian,in the case there is neither unevenness nor undulation on the surface ofwafer table WTB, focus control accuracy of the same level as the case ofthe shot area on the meridian can be secured. In the case there isunevenness or undulation on the surface of wafer table WTB, however,focus control accuracy depends on accuracy of traverse-Z-movingcorrection (to be described later). Further, in the cases such as whenmoving wafer stage WST, for example, in the X-axis direction in order toexpose the shot areas other than the one on the meridian, maincontroller 20 performs the transfer of the measurement values between aplurality of Z sensors along with the movement of wafer stage WST.

Next, focus calibration will be described. The focus calibration meansthe operation in which the processing (focus calibration formerprocessing) of obtaining a relation between surface position informationat end portions on one side and the other side of wafer table WTB in theX-axis direction in a certain datum state and a detection result(surface position information) at a representative detection point onthe measurement plate 30 surface of the multipoint AF system (90 a, 90b), and the processing (focus calibration latter processing) ofobtaining surface position information at end portions on one side andthe other side of wafer table WTB in the X-axis direction thatcorresponds to the best focus position of projection optical system PLdetected using aerial image measuring unit 45, in a state similar to thedatum state described above, are performed, and based on the processingresults, the processing of obtaining an offset at the representativedetection point of the multipoint AF system (90 a, 90 b), that is, thedeviation between the best focus position of projection optical systemPL and the detection origin of the multipoint AF system, or the like isperformed.

On the focus calibration, as is shown in FIG. 19A, main controller 20controls the position within the XY plane of wafer table WTB based ontwo X heads 66 facing X scales 39X₁ and 39X₂ respectively (X linearencoders 70B and 70D) and two Y heads 64 y ₂ and 64 y ₁ facing Y scales39Y₁ and 39Y₂ respectively (Y linear encoders 70A and 70C). In the stateof FIG. 19A, the centerline of wafer table WTB coincides with straightline LV. Further, in the state of FIG. 19A, wafer table WTB is locatedat a position in the Y-axis direction with which detection beams fromthe multipoint AF system (90 a, 90B) are irradiated to measurement plate30. Further, although omitted in the drawing, there is measurement stageMST on the +Y side of wafer table WTB (wafer stage WST) and water isheld in the space between CD bar 46 and wafer table WTB, and tip lens191 of projection optical system PL (refer to FIG. 31).

(a) In this state, main controller 20 performs the focus calibrationformer processing as follows. That is, while detecting surface positioninformation of the end portions on one side and the other side of wafertable WTB in the X-axis direction that is detected by Z sensors 72 a, 72b, 72 c and 72 d in the vicinity of each of detection points that arelocated at both end portions of the detection area of the multipoint AFsystem (90 a, 90 b), main controller 20 uses the surface positioninformation as a datum and detects surface position information of thesurface of measurement plate 30 (refer to FIG. 3) using the multipointAF system (90 a, 90 b). Thus, a relation between the measurement valuesof Z sensors 72 a, 72 b, 72 c and 72 d (surface position information atend portions on one side and the other side of wafer table WTB in theX-axis direction) and the detection result (surface positioninformation) at a detection point (the detection point located in thecenter or the vicinity thereof out of a plurality of detection points)on the measurement plate 30 surface of the multipoint AF system (90 a,90 b), in a state where the centerline of wafer table WTB coincides withstraight line LV, is obtained.

(b) Next, main controller 20 moves wafer stage WST in the +Y directionby a predetermined distance, and stops wafer stage WST at a positionwith which measurement plate 30 is located directly below projectionoptical system PL. Then, main controller 20 performs the focuscalibration latter processing as follows. That is, as is shown in FIG.19B, while controlling the position in the optical axis direction ofprojection optical system PL (Z-position) of measurement plate 30 (wafertable WTB), using surface position information as a datum, which ismeasured by a pair of Z sensors 74 _(1,4) and 74 _(2,4), and a pair of Zsensors 76 _(1,3) and 76 _(2,3) that measure surface positioninformation at the end portions on one side and the other side in theX-axis direction of wafer table WTB, main controller 20 measures anaerial image of a measurement mark formed on a mark plate (not shown) onreticle R or reticle stage RST by a slit-scan method using aerial imagemeasuring unit 45, and based on the measurement results, measures thebest focus position of projection optical system PL. In this case, as isshown in FIG. 19B, since liquid immersion area 14 is formed betweenprojection optical system PL and measurement plate 30 (wafer table WTB),the aerial image measurement described above is performed via projectionoptical system PL and water. Further, although omitted in FIG. 19B,since measurement plate 30 of aerial image measuring unit 45 and thelike are mounted on wafer stage WST (wafer table WTB) and thelight-receiving element and the like are mounted on measurement stageMST, the aerial image measurement described above is performed whilekeeping wafer stage WST and measurement stage MST in a contact state (ora proximity state) (refer to FIG. 33). By the measurement describedabove, the measurement values of Z sensors 74 _(1,4) and 74 _(2,4), and76 _(1,3) and 76 _(2,3) (i.e. surface position information at the endportions on one side and the other side in the X-axis direction of wafertable WTB) in a state where the centerline of wafer table WTB coincideswith straight line LV are obtained. These measurement values correspondto the best focus position of projection optical system PL.

(c) Thus, main controller 20 can obtain the offset at the representativedetection point of the multipoint AF system (90 a, 90 b), that is, thedeviation between the best focus position of projection optical systemPL and the detection origin of the multipoint AF system, based on therelation between the measurement values of Z sensors 72 a and 72 b, and72 c and 72 d (surface position information at the end portions on oneside and the other side in the X-axis direction of wafer table WTB) andthe detection result (surface position information) of the measurementplate 30 surface by the multipoint AF system (90 a, 90 b) that isobtained in the focus calibration former processing in the above (a),and based on the measurement values of Z sensors 74 _(1,4) and 74_(2,4), and 76 _(1,3) and 76 _(2,3) (i.e. surface position informationat the end portions on one side and the other side in the X-axisdirection of wafer table WTB) corresponding to the best focus positionof projection optical system PL that are obtained in the focuscalibration latter processing in the above (b). In the embodiment, therepresentative detection point is, for example, the detection point inthe center of the plurality of detection points or in the vicinitythereof, but the number and/or the position may be arbitrary. In thiscase, main controller 20 performs adjustment of the detection origin ofthe multipoint AF system so that the offset at the representativedetection point becomes zero. For example, the adjustment may beperformed optically by performing angle adjustment of a plane parallelplate (not shown) inside photodetection system 90 b, or the detectionoffset may be electrically adjusted. Alternatively, the offset may bestored, without performing adjustment of the detection origin. Herein,adjustment of the detection origin is to be performed in the opticalmethod referred to above. Thus, the focus calibration of the multipointAF system (90 a, 90 b) ends. Incidentally, in the optical adjustment ofthe detection origin, since it is difficult to make the offsets at allthe remaining detection points other than the representative detectionpoint be zero, the offsets after the optical adjustment at the remainingdetection points are preferably stored.

Next, offset correction of detection values among a plurality oflight-receiving elements (sensors) that individually correspond to aplurality of detection points of the multiple AF system (90 a, 90 b)(hereinafter, referred to as offset correction among AF sensors) will bedescribed.

On the offset correction among AF sensors, as is shown in FIG. 20A, maincontroller 20 makes irradiation system 90 a of the multipoint AF system(90 a, 90 b) irradiate detection beams to CD bar 46 equipped with apredetermined datum plane, and loads output signals from photodetectionsystem 90 b of the multipoint AF system (90 a, 90 b) that receives thereflected lights from the CD bar 46 surface (datum plane).

In this case, if the CD bar 46 surface is set parallel to the XY plane,main controller 20 can perform the offset correction among AF sensors byobtaining a relation among the detection values (measurement values) ofa plurality of sensors that individually correspond to a plurality ofdetection points based on the output signals loaded in the mannerdescribed above and storing the relation in a memory, or electricallyadjusting the detection offset of each sensor so that the detectionvalues of all the sensors become, for example, the same value as thedetection value of a sensor that corresponds to the representativedetection point on the focus calibration described above.

In the embodiment, however, as is shown in FIG. 20A, main controller 20detects a tilt of the CD bar 46 surface using Z sensors 72 a, 72 b, 72 cand 72 d when loading the output signals from photodetection system 90 bof the multipoint AF system (90 a, 90 b), and therefore, the CD bar 46surface does not always have to be set parallel to the XY plane. Inother words, as is modeled in FIG. 20B, when it is assumed that thedetection value at each detection point is the value as severallyindicated by arrows in the drawing and a line that connects the upperends of the detection values has unevenness as shown in a dotted line inthe drawing, each detection value only has to be adjusted so that theline that connects the upper ends of the detection values becomes a lineshown in a solid line in the drawing.

Next, traverse-Z-moving correction, in which information used to correctinfluence of unevenness related to the X-axis direction of the wafertable WTB surface, to be more accurate, of the second water repellentplate 28 b surface is obtained, will be described. Herein, thetraverse-Z-moving correction is performed by simultaneously loading themeasurement values of the Z sensors that detect position information ofeither side areas in a horizontal direction on the surface of secondwater repellent plate 28 b of wafer table WTB and the detection valuesof surface position information of the wafer by the multipoint AF systemat predetermined sampling intervals while moving wafer table WTB in theX-axis direction.

On the traverse-Z-moving correction, similar to the case of the focusmapping described above, as is shown in FIG. 21A, main controller 20controls the position within the XY plane of wafer table WTB based ontwo X heads 66 facing X scales 39X₁ and 39X₂ respectively (X linearencoders 70B and 70D) and two Y heads 64 y ₂ and 64 y ₁ facing Y scales39Y₁ and 39Y₂ respectively (Y linear encoders 70A and 70C). In the stateof FIG. 21A, the centerline of wafer table WTB is located on the +X sideof straight line LV, and main controller 20 measures surface positioninformation of the points in the vicinity of the −X side end portions ofthe either side areas on the surface of second water repellent plate 28b of wafer table WTB using Z sensors 72 a and 72 b, and Z sensors 72 cand 72 d, and at the same time, detects surface position information ofthe wafer using the multipoint AF system (90 a, 90 b).

Subsequently, main controller 20 moves wafer stage WST in the −Xdirection at a predetermined speed as is indicated by an outline arrowin FIG. 21A. During the movement, main controller 20 repeatedly executessimultaneous loading of the measurement values of Z sensors 72 a and 72b and Z sensors 72 c and 72 d and the detection values of the multipointAF system (90 a, 90 b) at predetermined sampling intervals. Then, as isshown in FIG. 21B, at the point in time when the simultaneous loadingdescribed above in a state where Z sensors 72 a and 72 b and Z sensors72 c and 72 d face the points in the vicinity of the +X end portions ofthe either side areas on the surface of second water repellent plate 28b of wafer table WTB is completed, main controller 20 ends theoperation.

Then, main controller 20 obtains a relation between the surface positioninformation at each detection point of the multipoint AF system (90 a,90 b) and the surface position information by Z sensors 72 a to 72 dthat has been simultaneously loaded. Then, main controller 20 computesunevenness related to the X-axis direction of the surface of secondwater repellent plate 28 b from a plurality of relations that have beenobtained at different sampling timings. In other words, in this case,since the offset among sensors of the multipoint AF system (90 a, 90 b)has been adjusted, the detection values of the sensors corresponding toany detection points should be the same value as far as the same pointon the surface of second water repellent plate 28 b is detected.Accordingly, the differences among the detection values obtained whendetecting the same point on the surface of second water repellent plate28 b by the sensors corresponding to different detection points aredirectly reflected by unevenness of the surface of second waterrepellent plate 28 b and position variation in the Z-axis direction ofthe wafer table during the movement. Then, by making use of thisrelation, unevenness related to the X-axis direction of the surface ofsecond water repellent plate 28 b is computed from the plurality ofrelations that have been obtained at different sampling timings.

In this manner, main controller 20 obtains information on positionvariation in the Z-axis direction of the wafer table WTB surface thatoccurs when wafer table WTB (wafer stage WST) moves in the X-axisdirection (is located at different X-positions), based on the resultsthat have been sequentially detected using the multipoint AF system (90a, 90 b) while moving wafer table WTB (wafer stage WST) in the X-axisdirection. Main controller 20 performs focus control of wafer W whileadding this information as a correction amount, on exposure.

Next, a parallel processing operation using wafer stage WST andmeasurement stage MST in exposure apparatus 100 of the embodiment willbe described based on FIGS. 22 to 36. Incidentally, during the operationdescribed below, main controller 20 performs opening/closing control ofeach valve of liquid supply unit 5 and liquid recovery unit 6 of localliquid immersion unit 8 as is described earlier, and the space on theoutgoing surface side of tip lens 191 of projection optical system PL isconstantly filled with water. However, description regarding control ofliquid supply unit 5 and liquid recovery unit 6 will be omitted in thefollowing description, in order to make the description easilyunderstandable. Further, the following description regarding theoperations will be made using many drawings, but the reference codes ofthe same members are shown in some drawings and not shown in the otherdrawings. That is, the reference codes shown are different in each ofthe drawings, but these drawings show the same configuration regardlessof existence or non-existence of the reference codes. The same is truealso in each of the drawings used in the description above.

FIG. 22 shows a state where exposure by a step-and-scan method is beingperformed to wafer W (in this case, to be a mid wafer of a certain lot(one lot containing 25 or 50 wafers), as an example) on wafer stage WST.At this point in time, measurement stage MST is moving following waferstage WST while keeping a predetermined distance between them.Therefore, the same distance as the predetermined distance is sufficientas a moving distance of measurement stage MST that is needed when goinginto the contact state (or proximity state) with wafer stage WSTdescribed above after the exposure ends.

During the exposure, main controller 20 controls the position (includingthe θz rotation) within the XY plane of wafer table WTB (wafer stageWST) based on the measurement values of two X heads 66 indicated bybeing circled in FIG. 22 that face X scales 39X₁ and 39X₂ respectively(X encoders 70B and 70D) and two Y heads 64 indicated by being circledin FIG. 22 that face Y scales 39Y₁ and 39Y₂ respectively (Y encoders 70Aand 70C). Further, main controller 20 controls the position in theZ-axis direction, and the θy rotation (rolling) and the θx rotation(pitching) of wafer table WTB, based on the measurement values of a pairof Z sensors 74 _(1,j) and 74 _(2,j), and a pair of Z sensors 76 _(1,q)and 76 _(2,q) that respectively face the end portions on one side andthe other side in the X-axis direction of the wafer table WTB surface.Incidentally, the position in the Z-axis direction and the θy rotation(rolling) of wafer table WTB may be controlled based on the measurementvalues of Z sensors 74 _(1,j) and 74 _(2,j), and 76 _(1,q) and 76 _(2,q)and the θx rotation (pitching) may be controlled based on themeasurement values of Y-axis interferometer 16. In either case, thecontrol of the position in the Z-axis direction, the θy rotation and θxrotation of wafer table WTB (focus leveling control of wafer W) duringthe exposure is performed based on the results of the above-describedfocus mapping performed beforehand.

Further, during the exposure, shutters 49A and 49B are set in a state ofclosing openings 51A and 51B, in order to prevent wafer stage WST andmeasurement stage MST from coming closer together than a predetermineddistance.

The foregoing exposure operation is performed by main controller 20repeating a moving operation between shots in which wafer stage WST ismoved to a scanning starting position (accelerating starting position)for exposure of each shot area on wafer W based on the result of theabove-described wafer alignment (EGA) performed beforehand, the latestbaselines of alignment systems AL1 and AL2 ₁ to AL2 ₄, and the like, anda scanning exposure operation in which a pattern formed on reticle R istransferred to each shot area by a scanning exposure method.Incidentally, the exposure operation described above is performed in astate where water is held in the space between tip lens 191 and wafer W.Further, the exposure operation is performed in the order from the shotarea located on the −Y side to the shot area located on the +Y side inFIG. 22.

Further, main controller 20 may also accumulate the measurement valuesof encoders 70A to 70D and the measurement values of interferometers 16and 126 during exposure and update the correction map described earlieras needed.

Then, as is shown in FIG. 23, before exposure to wafer W ends, forexample, before the last shot area is exposed when different shot areason wafer W are sequentially exposed, main controller 20 starts thelowering drive of shutters 49A and 49B via drive mechanisms 34A and 34B,and sets openings 51A and 51B in an opened state. After confirming thatshutters 49A and 49B are in a fully opened state via opening/closingsensor 101, main controller 20 moves measurement stage MST (measurementtable MTB) to the position shown in FIG. 24 by controlling stage drivesystem 124 based on the measurement value of Y-axis interferometer 18while maintaining the measurement value of X-axis interferometer 130 toa constant value. At this point in time, the end surface on the −Y sideof CD bar 46 (measurement table MTB) and the end surface on the +Y sideof wafer table WTB are in contact with each other. Incidentally, thenoncontact state (proximity state) may also be kept by, for example,monitoring the measurement values of the interferometer or the encoderthat measures the position of each table in the Y-axis direction andseparating measurement table MTB and wafer table WTB in the Y-axisdirection at a distance of around 300 μm.

Subsequently, as is shown in FIG. 25, while keeping the positionalrelation in the Y-axis direction between wafer table WTB and measurementtable MTB, main controller 20 starts an operation of driving measurementstage MST in the −Y direction and also starts an operation of drivingwafer stage WST toward unloading position UP. When these operations arestarted, in the embodiment, measurement stage MST is moved only in the−Y direction, and wafer stage WST is moved in the −Y direction and −Xdirection.

When main controller 20 drives wafer stage WST and measurement stage MSTsimultaneously as is described above, water that is held in the spacebetween tip lens 191 of projection unit PU and wafer W (water in liquidimmersion area 14) sequentially moves from wafer W to plate 28, CD bar46, and measurement table MTB, according to movement of wafer stage WSTand measurement stage MST to the −Y side. Incidentally, during theforegoing movement, the contact state (or proximity state) of wafertable WTB and measurement table MTB is maintained. Incidentally, FIG. 25shows a state right before water in liquid immersion area 14 isdelivered from plate 28 to CD bar 46.

When wafer stage WST and measurement stage MST are simultaneously andslightly driven further in the −Y direction from the state of FIG. 25,position measurement of wafer stage WST (wafer table WTB) by Y encoders70A and 70C cannot be performed. Therefore, right before that, maincontroller 20 switches the control of the Y-position and the θz rotationof wafer stage WST (wafer table WTB) from the control based on themeasurement values of Y encoders 70A and 700 to the control based on themeasurement value of Y-axis interferometer 16. Then, since after apredetermined period of time, measurement stage MST reaches a positionwhere the Sec-BCHK (interval) described earlier is performed as is shownin FIG. 26, main controller 20 stops measurement stage MST at theposition, and also drives further wafer stage WST toward unloadingposition UP while measuring the X-position of wafer stage WST by X head66 indicated by being circled in FIG. 26 that faces X scale 39X₁(X-linear encoder 70B) and measuring the Y-position, the θz rotation andthe like by Y-axis interferometer 16, and stops wafer stage WST atunloading position UP. Incidentally, in the state of FIG. 26, water isheld in the space between measurement table MTB and tip lens 191.

Subsequently, as is shown in FIGS. 26 and 27, main controller 20performs the Sec-BCHK (interval) in which relative positions of foursecondary alignment systems with respect to primary alignment system AL1are measured in the procedures described previously, using CD bar 46 ofmeasurement stage MST. In parallel with the Sec-BCHK (interval), maincontroller 20 gives the command and makes a drive system of an unloadarm (not shown) unload wafer W on wafer stage WST that stops atunloading position UP, and also drives wafer stage WST in the +Xdirection to move it to loading position LP with a vertical movement pinCT (not shown in FIG. 26, refer to FIG. 27), which has been drivenupward when performing the unloading, kept upward a predeterminedamount. In this case, the unloading of the wafer is performed asfollows: vertical movement pin CT supports wafer W from below and liftsthe wafer, and the unload arm proceeds to below wafer W, and thenvertical movement pin CT is slightly lowered or the unload arm isslightly raised or the like, and the wafer is delivered from verticalmovement pin CT to the unload arm.

Next, as is shown in FIG. 28, main controller 20 moves measurement stageMST to an optimal waiting position (hereinafter, referred to as an“optimal scrum waiting position”) used to shift a state of measurementstage MST from a state of being away from wafer stage WST to the contactstate (or proximity state) with wafer stage WST described previously,and closes shutters 49A and 49B in the foregoing procedures. In parallelwith this operation, main controller 20 gives the command and makes adrive system of a load arm (not shown) load new wafer W onto wafer tableWTB. The loading of wafer W is performed in the following procedures:wafer W held by the load arm is delivered from the load arm to verticalmovement pin CT whose state of being raised upward a predeterminedamount is maintained, and after the load arm is withdrawn, wafer W ismounted onto the wafer holder by vertical movement pin CT being loweredand the wafer is sucked by a vacuum chuck (not shown). In this case,since the state where vertical movement pin CT is raised upward apredetermined amount is maintained, the wafer loading can be performedin a shorter period of time, compared with the case where verticalmovement pin CT is driven downward to be housed inside the wafer holder.Incidentally, FIG. 28 shows the state where wafer W is loaded on wafertable WTB.

In the embodiment, the foregoing optimal scrum waiting position ofmeasurement stage MST is appropriately set in accordance with theY-coordinates of the alignment marks arranged in the alignment shotareas on the wafer. With this setting, an operation of movingmeasurement stage MST to the optimal scrum waiting position becomesunnecessary when the state of measurement stage MST shifts to thecontact state (or proximity state) described above, and therefore, thenumber of movement of measurement stage MST can be decreased by onecompared with the case where measurement stage MST is made to wait at aposition that is away from the optimal scrum waiting position. Further,in the embodiment, as the optimal scrum waiting position describedabove, the optimal scrum waiting position is set so that the shift tothe contact state (or proximity state) described above can be performedat a position where wafer stage WST stops for the wafer alignmentdescribed above.

Next, as is shown in FIG. 29, main controller 20 moves wafer stage WSTfrom loading position LP to a position with which the position offiducial mark FM on measurement plate 30 is set within the field(detection area) of primary alignment system AL1 (i.e. the positionwhere the foregoing Pri-BCHK former processing is performed). In themiddle of the movement, main controller 20 switches control of theposition within the XY plane of wafer table WTB from the control basedon the measurement value of encoder 70B regarding the X-axis directionand the measurement value of Y-axis interferometer 16 regarding theY-axis direction and the θz rotation, to the control based on themeasurement values of two X heads 66 indicated by being circled in FIG.29 that face X scales 39X₁ and 39X₂ (encoders 70B and 70D) and themeasurement values of two Y heads 64 y ₂ and 64 y ₁ indicated by beingcircled in FIG. 29 that face Y scales 39Y₁ and 39Y₂ (encoders 70A and70C).

Then, main controller 20 performs the Pri-BCHK former processing inwhich fiducial mark FM is detected using primary alignment system AL1.At this point in time, measurement stage MST is waiting at the optimalscrum waiting position described above.

Next, main controller 20 starts movement of wafer stage WST in the +Ydirection toward a position where the alignment marks arranged in thethree first alignment shot areas AS (refer to FIG. 12C) are detected,while controlling the position of wafer stage WST based on themeasurement values of the four encoders described above. After startingthe movement of wafer stage WST in the +Y direction, main controller 20opens shutters 49A and 49B in the procedures described earlier, andpermits the further approaching of wafer stage WST and measurement stageMST. Further, main controller 20 confirms the opening of shutters 49Aand 49B based on the detection result of opening/closing sensor 101.

Then, when wafer stage WST reaches the position shown in FIG. 30, maincontroller 20 detects that wafer stage WST and measurement stage MSTcome into contact with each other (or come closer together at a distanceof around 300 μm), based on the outputs of collision detection sensors43B and 43D, and immediately stops wafer stage WST. Prior to thisoperation, main controller 20 activates (turns ON) Z sensors 72 a to 72d and starts measurement of the Z-position and the tilt (the θy rotationand the θx rotation) of wafer table WTB at the point in time when all ofor part of Z sensors 72 a to 72 d face(s) wafer table WTB, or beforethat point in time.

After the stop of wafer stage WST, main controller 20 almostsimultaneously and individually detects the alignment marks arranged inthe three first alignment shot areas AS (refer to star-shaped marks inFIG. 30) using primary alignment system AL1 and secondary alignmentsystems AL2 ₂ and AL2 ₃, and links the detection results of threealignment systems AL1, AL2 ₂ and AL2 ₃ and the measurement values of thefour encoders at the time of the detection, and stores them in a memory(not shown). Incidentally, the simultaneous detection of the alignmentmarks arranged in the three first alignment shot areas AS in this caseis performed while changing the relative positional relation in theZ-axis direction (focus direction) between a plurality of alignmentsystems AL1 and AL2 ₁ to AL2 ₄ and wafer W mounted on wafer table WTB bychanging the Z-position of wafer table WTB, as is described previously.

As is described above, in the embodiment, the shift to the contact state(or proximity state) of measurement stage MST and wafer stage WST iscompleted at the position where detection of the alignment marks in thefirst alignment shot areas AS is performed, and from the position, themovement in the +Y direction (step movement toward a position where thealignment marks arranged in the five second alignment shot areas AS aredetected as described previously) of both stages WST and MST in thecontact state (or proximity state) is started by main controller 20.Prior to the start of movement in the +Y direction of both stages WSTand MST, as is shown in FIG. 30, main controller 20 starts irradiationof detection beams of the multipoint AF system (90 a, 90 b) to wafertable WTB. With this operation, the detection area of the multipoint AFsystem is formed on wafer table WTB.

Then, during the movement of both stages WST and MST in the +Ydirection, when both stages WST and MST reach the position shown in FIG.31, main controller 20 performs the focus calibration former processingdescribed above, and obtains a relation between the measurement valuesof Z sensors 72 a, 72 b, 72 c and 72 d (surface position information atthe end portions on one side and the other side in the X-axis directionof wafer table WTB) and the detection result (surface positioninformation) of the measurement plate 30 surface by the multipoint AFsystem (90 a, 90 b) in a state where the centerline of wafer table WTBcoincides with straight line LV. At this point in time, liquid immersionarea 14 is formed near the boundary between CD bar 46 and wafer tableWTB. That is, water in liquid immersion area 14 is about to be deliveredfrom CD bar 46 to wafer table WTB.

Then, when both stages WST and MST further move in the +Y directionwhile keeping their contact state (or proximity state) and reach theposition shown in FIG. 32, main controller 20 almost simultaneously andindividually detects the alignment marks arranged in the five secondalignment shot areas AS (refer to star-shaped marks in FIG. 32) usingfive alignment systems AL₁ and AL2 ₁ to AL2 ₄, links the detectionresults of five alignment systems AL₁ and AL2 ₁ to AL2 ₄ and themeasurement values of the four encoders at the time of the detection,and stores them in a memory (not shown). Incidentally, the simultaneousdetection of the alignment marks' arranged in the five second alignmentshot areas AS in this case is also performed while changing theZ-position of wafer table WTB, as is described earlier.

Further, at this point in time, since the X head that faces X scale 39X₁and is located on straight line LV does not exist, main controller 20controls the position within the XY plane of wafer table WTB based onthe measurement values of X head 66 facing X scale 39X₂ (X linearencoder 70D) and Y linear encoders 70A and 70C.

As is described above, in the embodiment, position information(two-dimensional position information) of eight alignment marks in totalcan be detected at the point in time when detection of the alignmentmarks in the second alignment shot areas AS ends. Then, at this stage,main controller 20 obtains the scaling (shot magnification) of wafer Wby, for example, performing a statistical computation by the EGA methoddescribed above using the position information, and based on thecomputed shot magnification, main controller 20 may also adjust opticalproperties of projection optical system PL, for example, the projectionmagnification. In the embodiment, optical properties of projectionoptical system PL are adjusted by controlling adjusting unit 68 (referto FIG. 8) that adjusts the optical properties of projection opticalsystem PL, by driving a specific movable lens constituting projectionoptical system PL or changing the pressure of gas inside the airtightroom that is formed between specific lenses constituting projectionoptical system PL, or the like. That is, at the stage where alignmentsystems AL1 and AL2 ₁ to AL2 ₄ have ended detection of the predeterminednumber (eight, in this case) of the marks on wafer W, main controller 20may also control adjusting unit 68 so that adjusting unit 68 adjusts theoptical properties of projection optical system PL based on thedetection results. Incidentally, the number of marks is not limited toeight, or a half of the total number of marks subject to detection, butonly has to be the number, for example, required for computing thescaling of the wafer or the like.

Further, after the simultaneous detection of the alignment marksarranged in the five second alignment shot areas AS ends, maincontroller 20 starts again movement in the +Y direction of both stagesWST and MST in the contact state (or proximity state), and at the sametime, starts the focus mapping described earlier using Z sensors 72 a to72 d and the multipoint AF system (90 a, 90 b), as is shown in FIG. 32.

Then, when both stages WST and MST reach the position with whichmeasurement plate 30 is located directly below projection optical systemPL shown in FIG. 33, main controller 20 performs the Pri-BCHK latterprocessing described earlier and the focus calibration latter processingdescribed earlier.

Then, main controller 20 computes the baseline of primary alignmentsystem AL1 based on the result of the Pri-BCHK former processingdescribed earlier and the result of the Pri-BCHK latter processing.Along with this operation, based on a relation between the measurementvalues of Z sensors 72 a, 72 b, 72 c and 72 d (surface positioninformation at the end portions on one side and the other side in theX-axis direction of wafer table WTB) and the detection result (surfaceposition information) of the measurement plate 30 surface by themultipoint AF system (90 a, 90 b) that has been obtained in the focuscalibration former processing, and based on the measurement values of Zsensors 74 _(1,4), 74 _(2,4), 76 _(1,3) and 76 _(2,3) (i.e. surfaceposition information at the end portions on one side and the other sidein the X-axis direction of wafer table WTB) corresponding to the bestfocus position of projection optical system PL that have been obtainedin the focus calibration latter processing, main controller 20 obtainsthe offset at a representative detection point of the multipoint AFsystem (90 a, 90 b), and adjusts the detection origin of the multipointAF system in the optical method described previously so that the offsetbecomes zero.

In this case, from the viewpoint of throughput, only one of the Pri-BCHKlatter processing and the focus calibration latter processing may beperformed, or the procedure may shift to the next processing withoutperforming both processings. As a matter of course, in the case thePri-BCHK latter processing is not performed, the Pri-BCHK formerprocessing does not need to be performed either. And, in this case, maincontroller 20 only has to move wafer stage WST from loading position LPto a position at which the alignment marks arranged in the firstalignment shot areas AS are detected.

Incidentally, in the state of FIG. 33, the focus mapping is beingcontinued.

When wafer stage WST reaches the position shown in FIG. 34 by movementin the +Y direction of both stages WST and MST in the contact state (orproximity state) described above, main controller 20 stops wafer stageWST at that position, and also continues the movement of measurementstage MST in the +Y direction without stopping it. Then, main controller20 almost simultaneously and individually detects the alignment marksarranged in the five third alignment shot areas AS (refer to star-shapedmarks in FIG. 34) using five alignment systems AL1 and AL2 ₁ to AL2 ₄,links the detection results of five alignment systems AL1 and AL2 ₁ andAL2 ₄ and the measurement values of the four encoders at the time of thedetection and stores them in a memory (not shown). Incidentally, thesimultaneous detection of the alignment marks arranged in the five thirdalignment shot areas AS in this case is also performed while changingthe Z-position of wafer table WTB, as is described previously. Further,also at this point in time, the focus mapping is being continued.

On the other hand, after a predetermined period of time from the stop ofwafer stage WST described above, shock absorbers 47A and 47B withdrawfrom openings 51A and 51B formed at X-axis stator 80, and the state ofmeasurement stage MST and wafer stage WST shifts from the contact state(or proximity state) to the separation state. After the shift to theseparation state, main controller 20 sets openings 51A and 51B in aclosed state by driving shutters 49A and 49B upward via drive mechanisms34A and 34B, and when measurement stage MST reaches an exposure startwaiting position where measurement stage MST waits until exposure isstarted, main controller 20 stops measurement stage MST at the position.

Next, main controller 20 starts movement of wafer stage WST in the +Ydirection toward a position at which the alignment marks arranged in thethree fourth alignment shot areas AS are detected. At this point intime, the focus mapping is being continued. Meanwhile, measurement stageMST is waiting at the exposure start waiting position described above.

Then, when wafer stage WST reaches the position shown in FIG. 35, maincontroller 20 immediately stops wafer stage WST, and almostsimultaneously and individually detects the alignment marks arranged inthe three fourth alignment shot areas AS on wafer W (refer tostar-shaped marks in FIG. 35) using primary alignment system AL1 andsecondary alignment systems AL2 ₂ and AL2 ₃, links the detection resultsof three alignment systems AL1, AL2 ₂ and AL2 ₃ and the measurementvalues of the four encoders at the time of the detection, and storesthem in a memory (not shown). Incidentally, the simultaneous detectionof the alignment marks arranged in the three fourth alignment shot areasAS in this case is also performed while changing the Z-position of wafertable WTB, as is described previously. Also at this point in time, thefocus mapping is being continued, and measurement stage MST is stillwaiting at the exposure start waiting position. Then, main controller 20computes array information (coordinate values) of all the shot areas onwafer W on the XY coordinate system that is set by the measurement axesof the four encoders, for example, by performing a statisticalcomputation by the EGA method described earlier, using the detectionresults of 16 alignment marks in total obtained as is described aboveand the corresponding measurement values of the four encoders.

Next, main controller 20 continues the focus mapping while moving waferstage WST in the +Y direction again. Then, when the detection beam fromthe multipoint AF system (90 a, 90 b) begins to miss the wafer Wsurface, as is shown in FIG. 36, main controller 20 ends the focusmapping. After that, based on the result of the foregoing waferalignment (EGA), the latest measurement results of the baselines of fivealignment systems AL1 and AL2 ₁ to AL2 ₄, and the like, main controller20 performs exposure by a step-and-scan method in a liquid immersionexposure method and sequentially transfers a reticle pattern to aplurality of shot areas on wafer W. Afterwards, the similar operationsare repeatedly performed to the remaining wafers within the lot.

As is described above, according to the embodiment, a partial section ofaerial image measuring unit 45 is arranged at wafer table WTB (waferstage WST) and part of the remaining section is arranged at measurementstage MST, and aerial image measuring unit 45 measures an aerial imageof a measurement mark formed by projection optical system PL. Therefore,for example, at the time of the focus calibration described previously,when aerial image measuring unit 45 measures the best focus position ofprojection optical system PL, the measurement can be performed using theposition of wafer table WTB (wafer stage WST), at which a partialsection of aerial image measuring unit 45 is arranged, in a directionparallel to the optical axis of projection optical system PL as a datumof the best focus position. Accordingly, when exposing a wafer withillumination light IL, the position of wafer table WTB (wafer stage WST)in a direction parallel to the optical axis of projection optical systemPL is adjusted with high precision based on the measurement result ofthe best focus position. Further, since only a partial section of aerialimage measuring unit 45 is arranged at wafer table WTB (wafer stageWST), wafer table WTB (wafer stage WST) is not increased in size and theposition controllability can favorably be secured. Incidentally, thewhole remaining section of aerial image measuring unit 45 does not haveto be arranged at measurement stage MST, but the remaining section mayalso be arranged partially at measurement stage MST and outside themeasurement stage MST, respectively.

Further, according to the embodiment, Y-axis interferometer 18 andX-axis interferometer 130 measure position information of measurementstage MST, and four linear encoders 70A to 70D measure positioninformation of wafer table WTB (wafer stage WST). Herein, linearencoders 70A to 70D are reflective encoders that include a plurality ofgratings (i.e. Y scales 39Y₁ and 39Y₂, or X scales 39X₁ and 39X₂) thatare placed on wafer table WTB and have a grating in a predeterminedpitch whose periodic direction is a direction parallel to the Y-axis orthe X-axis respectively, and a plurality of heads (Y heads 64 or X heads66) to which scales 39Y₁, 39Y₂, 39X₁ and 39X₂ are placed facing.Therefore, in linear encoders 70A to 70D, the optical path length of thebeam irradiated from each head to the facing scale (grating) is muchshorter, compared with those of Y-axis interferometer 18 and X-axisinterferometer 130, and therefore, the beam is difficult to be affectedby air fluctuations, and short-term stability of the measurement valuesis superior to those of Y-axis interferometer 18 and X-axisinterferometer 130. Accordingly, it becomes possible to stably performposition control of wafer table WTB (wafer stage WST) holding a wafer.

Further, according to the embodiment, the placement distance in theX-axis direction between a plurality of Y heads 64 whose measurementdirection is the Y-axis direction is narrower than a width in the X-axisdirection of Y scale 39Y₁ or 39Y₂, and the placement distance in theY-axis direction between a plurality of X heads 66 whose measurementdirection is the X-axis direction is narrower than a width in the Y-axisdirection of X scale 39X₁ or 39X₂. Therefore, when moving wafer tableWTB (wafer stage WST), the Y-position of wafer table WTB (wafer stageWST) can be measured based on the measurement values of Y linear encoder70A or 70C that irradiates detection lights (beams) to Y scale 39Y₁ or39Y₂, while sequentially switching a plurality of Y heads 64, and inparallel with this operation, the X-position of wafer table WTB (waferstage WST) can be measured based on the measurement values of X linearencoder 70B or 70D that irradiates detection lights (beams) to X scale39X₁ or 39X₂, while sequentially switching a plurality of X heads 66.

Further, according to the embodiment, when moving wafer table WTB (waferstage WST) in the Y-axis direction for obtaining the correctioninformation on grating pitch of the scales described above, maincontroller 20 obtains correction information (correction information ongrating warp) used to correct warp of each grating line 37 thatconstitutes X scales 39X₁ and 39X₂, in the procedures describedpreviously. Then, while correcting the measurement values obtained fromhead units 62B and 62D based on the Y-position information of wafertable WTB (wafer stage WST) and the correction information on gratingwarp of X scales 39X₁ and 39X₂, (and the correction information ongrating pitch), main controller 20 performs the driving of wafer tableWTB (wafer stage WST) in the X-axis direction using X scales 39X₁ and39X₂ and head units 62B and 62D. Accordingly, it becomes possible toaccurately perform the driving of wafer table WTB (wafer stage WST) inthe X-axis direction using head units 62B and 62D that use X scales 39X₁and 39X₂ (encoders 70B and 70D), without being affected by the warp ofeach grating constituting X scales 39X₁ and 39X₂. Further, by performingthe similar operation to the above operation also with respect to theY-axis direction, the driving of wafer table WTB (wafer stage WST) inthe Y-axis direction can also be performed with good accuracy.

Further, according to the embodiment, while wafer stage WST is movinglinearly in the Y-axis direction, surface position information of thewafer W surface is detected by the multipoint AF system (90 a, 90 b)having a plurality of detection points that are set at a predetermineddistance in the X-axis direction, and also the alignment marks whosepositions are different from one another on wafer W are detected by aplurality of alignment systems AL1 and AL2 ₁ to AL2 ₄ having thedetection areas that are arrayed in a line along the X-axis direction.In other words, only by wafer stage WST (wafer W) linearly passingthough the plurality of detection points (detection area AF) of themultipoint AF system (90 a, 90B) and the detection areas of a pluralityof alignment systems AL1 and AL2 ₁ to AL2 ₄, detection of surfaceposition information on the substantially entire surface of wafer W anddetection of all the alignment marks to be detected on wafer W (e.g. thealignment marks in the alignment shot areas in the EGA) are finished,and therefore, the throughput can be improved, compared with the casewhere a detection operation of alignment marks and a detection operationof surface position information (focus information) are independently(separately) performed.

In the embodiment, as is obvious from the description of the parallelprocessing operations using wafer stage WST and measurement stage MSTdescribed above, in the middle of movement of wafer stage WST from theloading position toward the exposure position (exposure area IA) (i.e.during the movement of wafer stage WST in the Y-axis direction), maincontroller 20 makes a plurality of alignment systems AL1 and AL2 ₁ toAL2 ₄ simultaneously detect a plurality of the marks (alignment marks inthe alignment shot areas) whose positions in the X-axis direction aredifferent on wafer W, and also makes the multipoint AF system (90 a,90B) detect surface position information of wafer W that passes throughthe detection areas of the plurality of alignment systems according tothe movement of wafer stage WST in the Y-axis direction. Therefore, thethroughput can be improved, compared with the case where a detectionoperation of alignment marks and a detection operation of surfaceposition information (focus information) are independently performed.Incidentally, in the embodiment, the loading position and the exposureposition are to be different in the X-axis direction, but the positionsin the X-axis direction may also be substantially the same. In thiscase, wafer stage WST can be moved substantially linearly from theloading position to the detection areas of the alignment systems (andthe multipoint AF system). Further, the loading position and theunloading position may be the same position.

Further, according to the embodiment, while measuring the position inthe Y-axis direction and the θz rotation (yawing) of wafer table WTB(wafer stage WST) based on the measurement values of a pair of Y heads64 y ₂ and 64 y ₁ facing a pair of Y scales 39Y₁ and 39Y₂ respectively(a pair of Y-axis linear encoders 70A and 70C), wafer table WTB (waferstage WST) can be moved in the Y-axis direction. Further, in this case,since movement of wafer table WTB (wafer stage WST) in the Y-axisdirection can be realized in a state where the relative positions in theX-axis direction of secondary alignment systems AL2 ₁ to AL2 ₄ withrespect to primary alignment system AL1 are adjusted according to thearray (such as the size) of the shot areas formed on wafer W, thealignment marks in a plurality of shot areas (e.g. alignment shot areas)whose positions in the Y-axis direction are the same and whose positionsin the X-axis direction are different on wafer W can be measuredsimultaneously by a plurality of alignment systems AL1 and AL2 ₁ to AL2₄.

Further, according to the embodiment, main controller 20 detects thealignment marks on wafer W using alignment systems AL1 and AL2 ₁ to AL2₄, while controlling the position of wafer table WTB (wafer stage WST)based on the measurement values by the encoder system (Y linear encoders70A and 70C, X linear encoders 70B and 70D). In other words, thealignment marks on wafer W can be detected using alignment systems AL1and AL2 ₁ to AL2 ₄ while controlling the position of wafer table WTB(wafer stage WST) with high precision based on the measurement values ofY heads 64 facing Y scales 39Y₁ and 39Y₂ respectively (Y linear encoders70A and 70C) and X heads 66 facing X scales 39X₁ and 39X₂ respectively(X linear encoders 70B and 70D).

Further, according to the embodiment, the number of detection points(the number of measurement points) of the alignment marks on wafer Wthat are simultaneously detected by alignment systems AL1 and AL2 ₁ toAL2 ₄ differs depending on the position within the XY plane of wafertable WTB (wafer stage WST). Therefore, for example, at the time of theforegoing wafer alignment or the like, when moving wafer table WTB(wafer stage WST) in a direction intersecting the X-axis, for example,in the Y-axis direction, it becomes possible to simultaneously detectthe alignment marks whose positions are different from one another onwafer W using the required number of alignment systems, in accordancewith the position of wafer table WTB (wafer stage WST) in the Y-axisdirection, in other words, in accordance with the placement (layout) ofthe shot areas on wafer W.

Further, according to the embodiment, at the stage where the alignmentmarks on wafer W to be detected by the alignment systems remain (e.g. atthe point in time when detection of the alignment marks arranged in thesecond alignment shot areas AS ends), in some cases, main controller 20controls adjusting unit 68 so that adjusting unit 68 adjusts the opticalproperties of projection optical system PL based on the detectionresults of a plurality of (e.g. 8) alignment marks on wafer W that havebeen detected by the alignment systems by then. In such cases, forexample, in the case detection of an image of a predeterminedmeasurement mark (or pattern) by projection optical system PL isperformed after the adjustment of the optical properties of projectionoptical system PL, even if the image of the measurement mark shifts dueto the adjustment, the image of the measurement mark after the shift ismeasured, and as a consequence, the shift of the image of themeasurement mark due to the adjustment of the optical properties ofprojection optical system PL does not become a measurement error factor.Further, since the adjustment described above is started based on thedetection results of the alignment marks that have been detected by thenbefore detection of all the alignment marks to be detected is finished,the adjustment can be performed in parallel with the detection operationof the remaining alignment marks. That is, in the embodiment, a periodof time required for the adjustment can be overlapped with a period oftime from when detection of the alignment marks in the third alignmentshot areas AS is started until when detection of the alignment marks inthe fourth alignment shot areas AS is finished. Thus, the throughput canbe improved, compared with the conventional art in which the adjustmentis started after detection of all the marks is finished.

Further, according to the embodiment, during a period from when anoperation (e.g. the Pri-BCHK former processing) of measuring thepositional relation between a projection position of an image of apattern (e.g. a pattern of reticle R) by projection optical system PLand a detection center of alignment system AL1 (baseline of alignmentsystem AL1) is started until when the operation is completed (e.g. thePri-BCHK latter processing is finished), a detection operation of thealignment marks (e.g. the alignment marks in the three first alignmentshot areas and the five second alignment shot areas) on wafer W byalignment systems AL1 and AL2 ₁ to AL2 ₄ is performed. That is, at leastpart of the detection operation of the marks by the alignment systemscan be performed in parallel with the measurement operation of thepositional relation. Accordingly, at the point in time when themeasurement operation of the positional relation is completed, at leastpart of the detection operation by the alignment systems of a pluralityof alignment marks to be detected on wafer W can be finished. Thus, thethroughput can be improved, compared with the case where the detectionoperation of a plurality of alignment marks by alignment systems isperformed before or after the measurement operation of the positionalrelation.

Further, according to the embodiment, during a period from when startinga detection operation by alignment systems AL1 and AL2 ₁ to AL2 ₄ of aplurality of alignment marks to be detected on wafer W (e.g. the waferalignment operation described above, i.e. a detection operation of 16alignment marks in total severally arranged in the first alignment shotareas AS to the fourth alignment shot areas AS) until before completingthe operation, main controller 20 performs a measurement operation ofthe positional relation between a projection position of an image of apattern of reticle R by projection optical system PL and a detectioncenter of alignment system AL1 (baseline of alignment system AL1). Thatis, the measurement operation of the positional relation can beperformed in parallel with part of the detection operation of the marksby the alignment systems. Accordingly, during a period when thedetection operation by alignment systems AL1 and AL2 ₁ to AL2 ₄ of aplurality of alignment marks to be detected on wafer W is performed, themeasurement operation of the positional relation can be finished. Thus,the throughput can be improved, compared with the case where themeasurement operation of the positional relation is performed before orafter the detection operation by alignment systems of a plurality ofalignment marks to be detected on wafer W.

Further, according to the embodiment, during a period from when adetection operation of a plurality of marks to be detected on wafer W(e.g. the wafer alignment operation described above, i.e. a detectionoperation of 16 alignment marks) is started until before the detectionoperation is completed, main controller 20 performs a state switchingoperation between a contact state of wafer table WTB and measurementtable MTB (or a proximity state of making both tables come closertogether, for example, at 300 μm or less) and a separation state ofseparating both tables. In other words, according to the embodiment,both tables (or both stages) are controlled so that the detectionoperation by the alignment systems of a plurality of marks to bedetected on wafer W is started in the contact state (or proximitystate), and the switching from the contact state (or proximity state) tothe separation state is performed before the detection operation of allthe plurality of marks is completed. Accordingly, during a period whenthe detection operation of a plurality of marks to be detected on waferW is performed, the state switching operation can be finished. Thus, thethroughput can be improved, compared with the case where the stateswitching operation is performed before or after the detection operationof a plurality of marks to be detected on wafer W.

Further, according to the embodiment, main controller 20 starts themeasurement operation of the baseline of alignment system AL1 in theseparation state, and ends the measurement operation in the contactstate (or proximity state).

Further, according to the embodiment, main controller 20 controls stagedrive system 124 (Z-leveling mechanism (not shown)) and alignment systemAL1 and AL2 ₁ to AL2 ₄ so that while changing a relative positionalrelation in the Z-axis direction (a focus direction) between theplurality of alignment systems and wafer W by the Z-leveling mechanism,the alignment marks whose positions are different from one another onwafer W are simultaneously detected by a plurality of correspondingalignment systems. In other words, while changing the relativepositional relation in the focus direction between the plurality ofalignment systems and wafer W simultaneously among the plurality ofalignment systems, the marks whose positions are different from oneanother on wafer W are simultaneously detected by a plurality ofcorresponding alignment systems. Thus, each alignment system can performthe mark detection, for example, in the most favorable focused state,and by preferentially using the detection result or the like, the markswhose positions are different from one another on wafer W can bedetected with good accuracy without being affected by unevenness of thewafer W surface and the best focus differences among the plurality ofalignments systems. Incidentally, in the embodiment, alignment systemsAL1 and AL2 ₁ to AL2 ₄ are to be placed substantially along the X-axisdirection. However, the method in which while changing the relativepositional relation in the focus direction between a plurality ofalignment systems and wafer W simultaneously among the plurality ofalignment systems, the marks whose positions are different from oneanother on wafer W are simultaneously measured by a plurality ofcorresponding alignment systems is also effective in other placements ofalignment systems different from the placement described above. Thepoint is that marks formed at positions different from one another onwafer W only have to be detected almost simultaneously with a pluralityof alignment systems.

Further, according to the embodiment, the encoder system, which includesencoders 70A to 70D whose measurement values have good short-termstability, and the like, measures position information of wafer tableWTB within the XY plane with high precision without being affected byair fluctuations or the like, and also the surface position measuringsystem, which includes Z sensors 72 a to 72 d, 74 _(1,1) to 74 _(2,6),76 _(1,1) to 76 _(2,6), and the like, measures position information ofwafer table WTB in the Z-axis direction orthogonal to the XY plane withhigh precision without being affected by air fluctuations or the like.In this case, since both of the encoder system and the surface positionmeasuring system directly measure the upper surface of wafer table WTB,simple and direct position control of wafer table WTB, and therefore, ofwafer W can be performed.

Further, according to the embodiment, on the focus mapping describedpreviously, main controller 20 simultaneously activates the surfaceposition measuring system and the multipoint AF system (90 a, 90 b), andconverts the detection results of the multipoint AF system (90 a, 90 b)into data, using the measurement results of the surface positionmeasuring system as datums. Accordingly, by obtaining the converted datain advance, it becomes possible to perform surface position control ofwafer W by only measuring position information of wafer table WTB in theZ-axis direction and position information in a tilt direction withrespect to the XY plane by the surface position measuring systemafterward, without obtaining surface position information of wafer W.Accordingly, in the embodiment, although the working distance betweentip lens 191 and the wafer W surface is short, focus-leveling control ofwafer W on exposure can be executed with good accuracy, withoutproblems.

In the embodiment, as is obvious from the description of the parallelprocessing operation using wafer stage WST and measurement stage MSTdescribed above, in the process in which wafer W moves from the position(loading position LP) where wafer W is carried to wafer stage WST to theposition where predetermined processing to wafer W, for example,exposure (pattern formation) is performed, main controller 20 performsthe simultaneous operation of the surface position measuring system andthe multipoint AF system (90 a, 90 b) and the data converting processing(focus mapping) described above.

Further, in the embodiment, in the process from when a detectionoperation by alignment systems AL1 and AL2 ₁ to AL2 ₄ of a plurality ofmarks to be detected (e.g. the wafer alignment operation describedabove) is started until when the detection operation of a plurality ofmarks is completed, main controller 20 starts the simultaneous operationof the surface position measuring system and the multipoint AF system(90 a, 90 b) and also starts the data converting processing.

Further, according to the embodiment, as is described above, since thesurface position of wafer table WTB, and thus, the surface position ofwafer W can be controlled with high precision, it becomes possible toperform highly accurate exposure hardly having exposure defect caused bysurface position control error, which makes it possible to form an imageof a pattern on wafer W without image blur.

Further, according to the embodiment, for example, prior to exposure,main controller 20 measures surface position information of wafer Wusing the detection values (measurement values) of the multipoint AFsystem (90 a, 90 b), and taking surface position information at endportions of wafer table WTB on one side and the other side in the X-axisdirection as a datum. Also on exposure, main controller 20 performsposition adjustment of wafer W in a direction parallel to optical axisAX of projection optical system PL and a tilt direction with respect tothe plane orthogonal to optical axis AX, taking surface positioninformation at end portions of wafer table WTB on one side and the otherside in the X-axis direction as a datum. Accordingly, although surfaceposition information of wafer W is measured prior to exposure, surfaceposition control of wafer W can be performed with high precision onactual exposure.

Incidentally, in the embodiment above, the case has been exemplifiedwhere a pair of Y scales 39Y₁ and 39Y₂ used for Y-axis directionposition measurement and a pair of X scales 39X₁ and 39X₂ used forX-axis direction position measurement are arranged on wafer table WTB,and corresponding to these scales, a pair of head units 62A and 62C areplaced on one side and the other side in the X-axis direction withprojection optical system PL in between, and two head units 62B and 62Dare placed on one side and the other side in the Y-axis direction withprojection optical system PL in between. However, the present inventionis not limited to this, and only one scale of at least either pair of Yscales 39Y₁ and 39Y₂ for Y-axis direction position measurement or Xscales 39X₁ and 39X₂ for X-axis direction position measurement may bearranged alone, not in pairs on wafer table WTB, or only one head unitof at least either of a pair of head units 62A and 62C or two head units62B and 62D may be arranged. Further, the direction in which the scalesare arranged and the direction in which head units are arranged are notlimited to orthogonal directions such as the X-axis direction and theY-axis direction as in the embodiment above, but only have to bedirections that intersect each other.

Incidentally, in the description above, the case has been describedwhere while wafer replacement is being performed on wafer stage WST, theSec-BCHK (interval) is performed using CD bar 46 of measurement stageMST. However, the present invention is not limited to this, and at leastone of irregular illuminance measurement (and illuminance measurement),aerial image measurement, wavefront aberration measurement and the likeis performed using the measurement members of measurement stage MST, andthe measurement result may also be reflected in exposure of a wafer thatis performed after that. Specifically, for example, adjustment ofprojection optical system PL can be performed by adjusting unit 68 basedon the measurement result.

Incidentally, in the embodiment above, the case has been described wherewafer table WTB is moved at a low speed (extremely low speed) at a levelin which short-term fluctuation of the measurement values of theinterferometers can be ignored when performing the calibration to obtainthe correction information on grating pitch of scales. However, thepresent invention is not limited to this, and wafer table WTB can alsobe moved at a speed which is not an extremely low speed. In this case,for example, in the case correction information on grating pitch of Yscales 39Y₁ and 39Y₂, or the like is obtained, correction information(e.g. correction map) of grating pitch of the Y scales may also beindependently obtained, by setting the wafer table at the positions thatare different in the X-axis direction, and while moving the wafer tablein the Y-axis direction as in the embodiment above at each of theX-positions, simultaneously loading the measurement values of encoders70A and 70C, the measurement value of Y-axis interferometer 16 and themeasurement values of head units 62A and 62C during the movement,setting up the simultaneous equations using the sampling values thathave been obtained in the twice-operations of simultaneous loading, andsolving the simultaneous equations.

Further, in the embodiment above, as is shown in FIG. 10A, an encoder bya diffraction interference method in which the light from the lightsource is branched by the optical element such as the beam splitter andtwo reflection mirrors to reflect the light after the branch areequipped is to be used as encoders 70A to 70F. However, the types ofencoders are not limited to this, and an encoder by a diffractioninterference method using three gratings, or an encoder equipped withlight reflection block that is disclosed in, for example, Kokai(Japanese Unexamined Patent Application Publication) No. 2005-114406 andthe like may also be used. Further, in the embodiment above, head units62A to 62D are to have a plurality of heads placed at a predetermineddistance. However, the present invention is not limited this, and asingle head may also be employed, which is equipped with a light sourcethat emits a light beam to an area elongated in the pitch direction ofthe Y scale or X scale, and multiple light-receiving elements that aredensely arrayed in the pitch direction of the Y scale or the X scale andreceive a reflected light (diffracted light) of the light beam from theY scale or X scale (diffraction grating).

Further, in the embodiment above, damage of the diffraction gratings mayalso be prevented by covering the reflective diffraction gratings with aprotection member (such as a thin film, or a glass plate) that cantransmit the detection lights from head units 62A to 62D. Further, inthe embodiment above, the reflective diffraction gratings are to bearranged on the upper surface of wafer stage WST substantially parallelto the XY plane, but the reflective diffraction gratings may also bearranged on the lower surface of wafer stage WST, for example. In thiscase, head units 62A to 62D are, for example, placed on the base plateto which the lower surface of wafer stage WST faces. Moreover, in theembodiment above, wafer stage WST is to be moved within the horizontalplane, but may also be moved within a plane that intersect thehorizontal plane (such as a ZX plane). Further, in the case reticlestage RST is two-dimensionally moved, an encoder system having theconfiguration similar to the above-described encoder system may also bearranged to measure position information of reticle stage RST.

Incidentally, in the embodiment above, interferometer system 118 is tobe capable of measuring position information of wafer stage WST indirections of five degrees of freedom (the X-axis, Y-axis, θx, θy and θzdirections), but may be capable of measuring also position informationin the Z-axis direction. In this case, at least at the time of exposureoperation, position control of wafer stage WST may also be performedusing the measurement values of the encoder system described above andthe measurement values of interferometer system 118 (including at leastposition information in the Z-axis direction). Interferometer system 118measures position information in the Z-axis direction of wafer stageWST, by arranging a reflection surface, which is inclined at apredetermined angle (e.g. 45 degrees) with respect to the XY plane, onthe side surface of wafer stage WST, and irradiating a measurement beamvia the reflection surface to a reflection surface arranged on, forexample, on the barrel platform or the measurement frame describedabove, as is disclosed in, for example, Kokai (Japanese UnexaminedPatent Application Publication) No. 2000-323404 (the corresponding U.S.Pat. No. 7,116,401), Kohyo (published Japanese translation ofInternational Publication for Patent Application) No. 2001-513267 (thecorresponding U.S. Pat. No. 6,208,407), and the like. Interferometersystem 118 can also measure position information in the θx directionand/or the θy direction, in addition to the Z-axis direction, using aplurality of measurement beams. In this case, the measurement beams usedto measure position information in the θx direction and/or the θydirection that are irradiated to the movable mirror of wafer stage WSTdo not have to be used.

Incidentally, in the embodiment above, a plurality of Z sensors 74_(i,j) and 76 _(p,q) are to be arranged at head units 62C and 62A.However, the present invention is not limited to this, and a surfaceposition sensor similar to the Z sensor may also be arranged on, forexample, the measurement frame. Further, a distance between the encoderhead or the Z sensor and the upper surface of the wafer stage ispreferably equal to or less than a distance between tip optical element191 of projection optical system PL and the upper surface of the waferstage, for example, shorter than the distance. Thus, the measurementaccuracy can be improved. In this case, a simple Z sensor is effective,precisely because it is difficult to arrange the AF sensor.

Incidentally, in the embodiment above, the lower surface of nozzle unit32 and the lower end surface of the tip optical element of projectionoptical system PL are to be substantially flush. However, the presentinvention is not limited to this, and for example, the lower surface ofnozzle unit 32 may also be placed closer to the image plane ofprojection optical system (i.e. to the wafer) than the outgoing surfaceof the tip optical element. That is, the configuration of local liquidimmersion unit 8 is not limited to the above-described configuration,and the configurations can be used, which are described in, for example,EP Patent Application Publication No. 1 420 298, the pamphlet ofInternational Publication No. 2004/055803, the pamphlet of InternationalPublication No. 2004/057590, the pamphlet of International PublicationNo. 2005/029559 (the corresponding U.S. Patent Application PublicationNo. 2006/0231206), the pamphlet of International Publication No.2004/086468 (the corresponding U.S. Patent Application Publication No.2005/0280791), Kokai (Japanese Unexamined Patent ApplicationPublication) No. 2004-289126 (the corresponding U.S. Pat. No.6,952,253), and the like. Further, as disclosed in the pamphlet ofInternational Publication No. 2004/019128 (the corresponding U.S. PatentApplication Publication No. 2005/0248856), the optical path on theobject plane side of the tip optical element may also be filled withliquid, in addition to the optical path on the image plane side of thetip optical element. Furthermore, a thin film that is lyophilic and/orhas dissolution preventing function may also be formed on the partialsurface (including at least a contact surface with liquid) or the entiresurface of the tip optical element. Incidentally, quartz has a highaffinity for liquid, and also needs no dissolution preventing film,while in the case of fluorite, at least a dissolution preventing film ispreferably formed.

Incidentally, in the embodiment above, pure water (water) is to be usedas liquid, however, the present invention is not limited to this asmatter of course. As the liquid, liquid that is chemically stable,having high transmittance to illumination light IL and safe to use, suchas a fluorine-containing inert liquid may be used. As thefluorine-containing inert liquid, for example, Fluorinert (the brandname of 3M United States) can be used. The fluorine-containing inertliquid is also excellent from the point of cooling effect. Further, asthe liquid, liquid which has a refractive index higher than pure water(a refractive index is around 1.44), for example, liquid having arefractive index equal to or higher than 1.5 may be used. As this typeof liquid, for example, a predetermined liquid having C—H binding or O—Hbinding such as isopropanol having a refractive index of about 1.50,glycerol (glycerin) having a refractive index of about 1.61, apredetermined liquid (organic solvent) such as hexane, heptane ordecane, or decalin (decahydronaphthalene) having a refractive index ofabout 1.60, or the like can be cited. Alternatively, a liquid obtainedby mixing arbitrary two or more of these liquids may be used, or aliquid obtained by adding (mixing) at least one of these liquids to(with) pure water may be used. Alternatively, as the liquid, a liquidobtained by adding (mixing) base or acid such as H⁺, Cs⁺, K⁺, Cl⁻, SO₄²⁻, or PO₄ ²⁻ to (with) pure water may be used. Moreover, a liquidobtained by adding (mixing) particles of Al oxide or the like to (with)pure water may be used. These liquids can transmit ArF excimer laserlight. Further, as the liquid, liquid, which has a small absorptioncoefficient of light, is less temperature-dependent, and is stable to aprojection optical system (tip optical member) and/or a photosensitiveagent (or a protection film (top coat film), an antireflection film, orthe like) coated on the surface of a wafer, is preferable. Further, inthe case an F₂ laser is used as the light source, fomblin oil may beselected. Further, as the liquid, a liquid having a higher refractiveindex to illumination light IL than that of pure water, for example, arefractive index of around 1.6 to 1.8 may be used. As the liquid,supercritical fluid can also be used. Further, the tip optical elementof projection optical system PL may be formed by quartz (silica), orsingle-crystal materials of fluoride compound such as calcium fluoride(fluorite), barium fluoride, strontium fluoride, lithium fluoride, andsodium fluoride, or may be formed by materials having a higherrefractive index than that of quartz or fluorite (e.g. equal to orhigher than 1.6). As the materials having a refractive index equal to orhigher than 1.6, for example, sapphire, germanium dioxide, or the likedisclosed in the pamphlet of International Publication No. 2005/059617,or kalium chloride (having a refractive index of about 1.75) or the likedisclosed in the pamphlet of International Publication No. 2005/059618can be used.

Further, in the embodiment above, the recovered liquid may be reused,and in this case, a filter that removes impurities from the recoveredliquid is preferably arranged in a liquid recovery unit, a recovery pipeor the like.

Further, in the embodiment above, the case has been described where theexposure apparatus is a liquid immersion type exposure apparatus.However, the present invention is not limited to this, but can also beemployed in a dry type exposure apparatus that performs exposure ofwafer W without liquid (water).

Incidentally, in the embodiment above, the case has been described wherethe present invention is applied to the exposure apparatus that isequipped with all of wafer stage WST (movable body), measurement sageMST (another movable body), the alignment systems (AL1, AL2 ₁ to AL2 ₄),the multipoint AF system (90 a, 90 b), the Z sensors, interferometersystem 118, the encoder system (70A to 70F) and the like, but thepresent invention is not limited to this. For example, the presentinvention can also be applied to an exposure apparatus in whichmeasurement stage MST or the like is not arranged. The present inventioncan be applied as far as an exposure apparatus is equipped with thewafer stage (movable body) and other partial constituents out of theabove-described constituents. As an example, the invention focusing onthe mark detection system, for example, can be applied as far as anexposure apparatus is equipped with at least wafer stage WST and thealignment systems. Further, it is a matter of course that both of theinterferometer system and the encoder system do not always have to bearranged.

Further, in the embodiment above, the case has been described whereaerial image measuring unit 45 is dividedly placed at different stages,specifically, at wafer stage WST and measurement stage MST. However, thesensor that is dividedly placed is not limited to the aerial imagemeasuring unit, but may be a wavefront aberration measuring instrumentor the like, for example. Further, the different stages do not limitedto the combination of the substrate stage and measurement stage.

Further, in the embodiment above, the case has been described where thepresent invention is applied to a scanning exposure apparatus by astep-and-scan method or the like. However, the present invention is notlimited to this, but may also be applied to a static exposure apparatussuch as a stepper. Even with the stepper or the like, by measuring theposition of a stage on which an object subject to exposure is mounted byencoders, generation of position measurement error caused by airfluctuations can substantially be nulled likewise. In this case, itbecomes possible to set the position of the stage with high precisionbased on correction information used to correct short-term fluctuationof the measurement values of the encoders using the measurement valuesof the interferometers and based on the measurement values of theencoders, and as a consequence, highly accurate transfer of a reticlepattern onto the object can be performed. Further, the present inventioncan also be applied to a reduction projection exposure apparatus by astep-and-stitch method that synthesizes a shot area and a shot area, anexposure apparatus by a proximity method, a mirror projection aligner,or the like. Moreover, the present invention can also be applied to amulti-stage type exposure apparatus equipped with plural wafer stages,as is disclosed in, for example, Kokai (Japanese Unexamined PatentApplication Publications) No. 10-163099 and No. 10-214783 (thecorresponding U.S. Pat. No. 6,590,634), Kohyo (published Japanesetranslation of International Publication for Patent Application) No.2000-505958 (the corresponding U.S. Pat. No. 5,969,441), the U.S. Pat.No. 6,208,407, and the like.

Further, the magnification of the projection optical system in theexposure apparatus of the embodiment above is not only a reductionsystem, but also may be either an equal magnifying system or amagnifying system, and projection optical system PL is not only adioptric system, but also may be either a catoptric system or acatadioptric system, and in addition, the projected image may be eitheran inverted image or an upright image. Moreover, exposure area IA towhich illumination light IL is irradiated via projection optical systemPL is an on-axis area that includes optical axis AX within the field ofprojection optical system PL. However, for example, as is disclosed inthe pamphlet of International Publication No. 2004/107011, exposure areaIA may also be an off-axis area that does not include optical axis AX,similar to a so-called inline type catadioptric system, in part of whichan optical system (catoptric system or catadioptric system) that hasplural reflection surfaces and forms an intermediate image at least onceis arranged, and which has a single optical axis. Further, theillumination area and exposure area described above are to have arectangular shape. However, the shape is not limited to rectangular, butmay also be circular arc, trapezoidal, parallelogram or the like.

Incidentally, a light source of the exposure apparatus in the embodimentabove is not limited to the ArF excimer laser, but a pulse laser lightsource such as a KrF excimer laser (output wavelength: 248 nm), an F₂laser (output wavelength: 157 nm), an Ar₂ laser (output wavelength: 126nm) or a Kr₂ laser (output wavelength: 146 nm), or an extra-highpressure mercury lamp that generates an emission line such as a g-line(wavelength: 436 nm) or an i-line (wavelength: 365 nm) can also be used.Further, a harmonic wave generating unit of a YAG laser or the like canalso be used. Besides, as is disclosed in, for example, the pamphlet ofInternational Publication No. 1999/46835 (the corresponding U.S. Pat.No. 7,023,610), a harmonic wave, which is obtained by amplifying asingle-wavelength laser beam in the infrared or visible range emitted bya DFB semiconductor laser or fiber laser as vacuum ultraviolet light,with a fiber amplifier doped with, for example, erbium (or both erbiumand ytteribium), and by converting the wavelength into ultraviolet lightusing a nonlinear optical crystal, may also be used.

Further, in the embodiment above, illumination light IL of the exposureapparatus is not limited to the light having a wavelength equal to ormore than 100 nm, and it is needless to say that the light having awavelength less than 100 nm may be used. For example, in recent years,in order to expose a pattern equal to or less than 70 nm, an EUVexposure apparatus that makes an SOR or a plasma laser as a light sourcegenerate an EUV (Extreme Ultraviolet) light in a soft X-ray range (e.g.a wavelength range from 5 to 15 nm), and uses a total reflectionreduction optical system designed under the exposure wavelength (e.g.13.5 nm) and the reflective mask has been developed. In the EUV exposureapparatus, the arrangement in which scanning exposure is performed bysynchronously scanning a mask and a wafer using a circular arcillumination can be considered, and therefore, the present invention canalso be suitably applied to such an exposure apparatus. Besides, thepresent invention can also be applied to an exposure apparatus that usescharged particle beams such as an electron beam or an ion beam.

Further, in the embodiment above, a transmissive type mask (reticle),which is a transmissive substrate on which a predetermined lightshielding pattern (or a phase pattern or a light attenuation pattern) isformed, is used. Instead of this reticle, however, as is disclosed in,for example, U.S. Pat. No. 6,778,257, an electron mask (which is alsocalled a variable shaped mask, an active mask or an image generator, andincludes, for example, a DMD (Digital Micromirror Device) that is a typeof a non-emission type image display device (spatial light modulator) orthe like) on which a light-transmitting pattern, a reflection pattern,or an emission pattern is formed according to electronic data of thepattern that is to be exposed may also be used.

Further, as is disclosed in, for example, the pamphlet of InternationalPublication No. 2001/035168, the present invention can also be appliedto an exposure apparatus (lithography system) that forms line-and-spacepatterns on a wafer by forming interference fringes on the wafer.

Moreover, the present invention can also be applied to an exposureapparatus that synthesizes two reticle patterns via a projection opticalsystem and almost simultaneously performs double exposure of one shotarea by one scanning exposure, as is disclosed in, for example, Kohyo(published Japanese translation of International Publication for PatentApplication) No. 2004-519850 (the corresponding U.S. Pat. No.6,611,316).

Further, an apparatus that forms a pattern on an object is not limitedto the exposure apparatus (lithography system) described above, and forexample, the present invention can also be applied to an apparatus thatforms a pattern on an object by an ink-jet method.

Incidentally, an object on which a pattern is to be formed (an objectsubject to exposure to which an energy beam is irradiated) in theembodiment above is not limited to a wafer, but may be other objectssuch as a glass plate, a ceramic substrate, a film member, or a maskblank.

The usage of the exposure apparatus is not limited to the exposureapparatus used for manufacturing semiconductor devices. The presentinvention can be widely applied also to, for example, an exposureapparatus for manufacturing liquid crystal display devices whichtransfers a liquid crystal display device pattern onto a square-shapedglass plate, and to an exposure apparatus for manufacturing organic EL,thin-film magnetic heads, imaging devices (such as CCDs), micromachines,DNA chips or the like. Further, the present invention can also beapplied to an exposure apparatus that transfers a circuit pattern onto aglass substrate or a silicon wafer not only when producing microdevicessuch as semiconductor devices, but also when producing a reticle or amask used in an exposure apparatus such as an optical exposureapparatus, an EUV exposure apparatus, an X-ray exposure apparatus, andan electron beam exposure apparatus.

Incidentally, the movable body drive system and the movable body drivemethod of the present invention can be applied not only to the exposureapparatus, but can also be applied widely to other substrate processingapparatuses (such as a laser repair apparatus, a substrate inspectionapparatus and the like), or to apparatuses equipped with a movable bodysuch as a stage that moves within a two-dimensional plane such as aposition setting apparatus for specimen or a wire bonding apparatus inother precision machines.

Further, the exposure apparatus (the pattern forming apparatus) of theembodiment above is manufactured by assembling various subsystems, whichinclude the respective constituents that are recited in the claims ofthe present application, so as to keep predetermined mechanicalaccuracy, electrical accuracy and optical accuracy. In order to securethese various kinds of accuracy, before and after the assembly,adjustment to achieve the optical accuracy for various optical systems,adjustment to achieve the mechanical accuracy for various mechanicalsystems, and adjustment to achieve the electrical accuracy for variouselectric systems are performed. A process of assembling varioussubsystems into the exposure apparatus includes mechanical connection,wiring connection of electric circuits, piping connection of pressurecircuits, and the like among various types of subsystems. Needless tosay, an assembly process of individual subsystem is performed before theprocess of assembling the various subsystems into the exposureapparatus. When the process of assembling the various subsystems intothe exposure apparatus is completed, a total adjustment is performed andvarious kinds of accuracy as the entire exposure apparatus are secured.Incidentally, the making of the exposure apparatus is preferablyperformed in a clean room where the temperature, the degree ofcleanliness and the like are controlled.

Incidentally, the above disclosures of the various publications, thepamphlets of the International Publications, and the U.S. PatentApplication Publication descriptions and the U.S. Patent descriptionsthat are cited in the embodiment above and related to exposureapparatuses and the like are each incorporated herein by reference.

Next, an embodiment of a device manufacturing method in which theforegoing exposure apparatus (pattern forming apparatus) is used in alithography process will be described.

FIG. 37 shows a flowchart of an example when manufacturing a device (asemiconductor chip such as an IC or an LSI, a liquid crystal panel, aCCD, a thin film magnetic head, a micromachine, and the like). As isshown in FIG. 37, first of all, in step 201 (design step), function andperformance design of device (such as circuit design of semiconductordevice) is performed, and pattern design to realize the function isperformed. Then, in step 202 (mask manufacturing step), a mask on whichthe designed circuit pattern is formed is manufactured. Meanwhile, instep 203 (wafer manufacturing step), a wafer is manufactured usingmaterials such as silicon.

Next, in step 204 (wafer processing step), the actual circuit and thelike are formed on the wafer by lithography or the like in a manner thatwill be described later, using the mask and the wafer prepared in steps201 to 203. Then, in step 205 (device assembly step), device assembly isperformed using the wafer processed in step 204. Step 205 includesprocesses such as the dicing process, the bonding process, and thepackaging process (chip encapsulation), and the like when necessary.

Finally, in step 206 (inspection step), tests on operation, durability,and the like are performed on the devices made in step 205. After thesesteps, the devices are completed and shipped out.

FIG. 38 is a flowchart showing a detailed example of step 204 describedabove. Referring to FIG. 38, in step 211 (oxidation step), the surfaceof wafer is oxidized. In step 212 (CDV step), an insulating film isformed on the wafer surface. In step 213 (electrode formation step), anelectrode is formed on the wafer by deposition. In step 214 (ionimplantation step), ions are implanted into the wafer. Each of the abovesteps 211 to 214 constitutes the pre-process in each stage of waferprocessing, and the necessary processing is chosen and is executed ateach stage.

When the above-described pre-process ends in each stage of waferprocess, post-process is executed as follows. In the post-process, firstin step 215 (resist formation step), a photosensitive agent is coated onthe wafer. Then, in step 216 (exposure step), the circuit pattern of themask is transferred onto the wafer by the exposure apparatus (patternforming apparatus) described above and the exposure method (patternforming method) thereof. Next, in step 217 (development step), the waferthat has been exposed is developed, and in step 218 (etching step), anexposed member of an area other than the area where resist remains isremoved by etching. Then, in step 219 (resist removing step), whenetching is completed, the resist that is no longer necessary is removed.

By repeatedly performing the pre-process and the post-process, multiplecircuit patterns are formed on the wafer.

By using the device manufacturing method of the embodiment describedabove, because the exposure apparatus (pattern forming apparatus) in theembodiment above and the exposure method (pattern forming method)thereof are used in the exposure step (step 216), exposure with highthroughput can be performed while maintaining the high overlay accuracy.Accordingly, the productivity of highly integrated microdevices on whichfine patterns are formed can be improved.

While the above-described embodiments of the present invention are thepresently preferred embodiments thereof, those skilled in the art oflithography systems will readily recognize that numerous additions,modifications, and substitutions may be made to the above-describedembodiments without departing from the spirit and scope thereof. It isintended that all such modifications, additions, and substitutions fallwithin the scope of the present invention, which is best defined by theclaims appended below.

What is claimed is:
 1. An exposure apparatus that exposes an object withan energy beam via an optical system, the apparatus comprising: a stagesystem that has a movable body to hold the object and moves the objectby driving the movable body; a measurement system that has a pluralityof heads respectively irradiating beams to a plurality of gratingmembers placed substantially parallel to a predetermined planeorthogonal to an optical axis of the optical system, and that measurespositional information of the movable body in a first direction and asecond direction orthogonal to each other in the predetermined plane andin a third direction orthogonal to the first and the second directions;a detection system placed apart from the optical system, that detectspositional information of the object by irradiating a measurement beamon the object held by the movable body; and a controller coupled to thestage system, that controls driving of the movable body based on thepositional information measured by the measurement system, in anexposure operation of the object, wherein in a detection operation ofthe object by the detection system, the positional information of themovable body is measured by the measurement system, and the controllerdrives the movable body using the stage system so that a positionalrelation between the grating members and the heads is changed from oneof a first state and a second state to the other, in the first state theplurality of grating members respectively facing the plurality of heads,and in the second state remaining grating members, excluding one gratingmember from the plurality of grating members, facing some of theplurality of heads.
 2. The exposure apparatus according to claim 1,wherein the controller drives the movable body using the stage system sothat the one grating member that does not face the head in the secondstate is switched among the plurality of grating members, according to amovement of the movable body.
 3. The exposure apparatus according toclaim 2, wherein the plurality of grating members are four gratingmembers, in the first state, the four grating members face four of theplurality of heads, respectively, and in the second state, three gratingmembers, excluding the one grating member from the four grating members,face three of the plurality of heads, respectively.
 4. The exposureapparatus according to claim 3, wherein the controller drives themovable body using the stage system so that the first state is changedto the second state where three grating members, excluding anothergrating member from the four grating members, face three of theplurality of heads, the another grating member being different from theone grating member.
 5. The exposure apparatus according to claim 3,wherein the controller drives the movable body using the stage system sothat one of the first state and the second state is changed to the otherin at least the exposure operation of the object.
 6. The exposureapparatus according to claim 5, wherein the controller uses correctioninformation on the grating member in control of the stage system.
 7. Theexposure apparatus according to claim 6, wherein the correctioninformation includes information on at least one of pitch anddeformation of the grating member.
 8. The exposure apparatus accordingto claim 5, wherein the controller controls the stage system tocompensate for a measurement error of the measurement system that occursdue to the grating member.
 9. A device manufacturing method, comprising:exposing an object using the exposure apparatus according to claim 1;and developing the exposed object.
 10. A method of making an exposureapparatus that exposes an object with an energy beam via an opticalsystem, the method comprising: providing a stage system that has amovable body to hold the object and moves the object by driving themovable body; providing a measurement system that has a plurality ofheads respectively irradiating beams to a plurality of grating membersplaced substantially parallel to a predetermined plane orthogonal to anoptical axis of the optical system, and that measures positionalinformation of the movable body in a first direction and a seconddirection orthogonal to each other in the predetermined plane and in athird direction orthogonal to the first and the second directions;providing a detection system placed apart from the optical system, thatdetects positional information of the object by irradiating ameasurement beam on the object held by the movable body; and providing acontroller coupled to the stage system, that controls driving of themovable body based on the positional information measured by themeasurement system, in an exposure operation of the object, wherein in adetection operation of the object by the detection system, thepositional information of the movable body is measured by themeasurement system, and the controller drives the movable body using thestage system so that a positional relation between the grating membersand the heads is changed from one of a first state and a second state tothe other, in the first state the plurality of grating membersrespectively facing the plurality of heads, and in the second stateremaining grating members, excluding one grating member from theplurality of grating members, facing some of the plurality of heads. 11.An exposure method of exposing an object with an energy beam via anoptical system, the method comprising: moving the object by a stagesystem having a movable body that holds the object; by a measurementsystem having a plurality of heads that respectively irradiate beams toa plurality of grating members placed substantially parallel to apredetermined plane orthogonal to an optical axis of the optical system,measuring positional information of the movable body in a firstdirection and a second direction orthogonal to each other in thepredetermined plane and in a third direction orthogonal to the first andthe second directions; detecting positional information of the object bya detection system that irradiates a measurement beam on the object heldby the movable body; and controlling the stage system based on thepositional information measured by the measurement system, in anexposure operation of the object, wherein in a detection operation ofthe object by the detection system, the positional information of themovable body is measured by the measurement system, and the movable bodyis driven by the stage system so that a positional relation between thegrating members and the heads is changed from one of a first state and asecond state to the other, in the first state the plurality of gratingmembers respectively facing the plurality of heads, and in the secondstate remaining grating members, excluding one grating member from theplurality of grating members, facing some of the plurality of heads. 12.The exposure method according to claim 11, wherein the movable body isdriven by the stage system so that the one grating member that does notface the head in the second state is changed among the plurality ofgrating members, according to movement of the movable body.
 13. Theexposure method according to claim 12, wherein the plurality of gratingmembers are four grating members, in the first state, the four gratingmembers face four of the plurality of heads, respectively, and in thesecond state, three grating members, excluding the one grating memberfrom the four grating members, face three of the plurality of heads,respectively.
 14. The exposure method according to claim 13, wherein themovable body is driven by the stage system so that the first state ischanged to the second state where three grating members, excludinganother grating member from the four grating members, face three of theplurality of heads, the another grating member being different from theone grating member.
 15. The exposure method according to claim 13,wherein the movable body is driven by the stage system so that one ofthe first state and the second state is changed to the other in at leastthe exposure operation of the object.
 16. The exposure method accordingto claim 15, wherein correction information on the grating member isused in control of the stage system.
 17. The exposure method accordingto claim 16, wherein the correction information includes information onat least one of pitch and deformation of the grating member.
 18. Theexposure method according to claim 15, wherein the stage system iscontrolled so that a measurement error of the measurement system thatoccurs due to the grating member is compensated for.
 19. A devicemanufacturing method, comprising: exposing an object using the exposuremethod according to claim 11; and developing the exposed object.